Communications jack having a flexible printed circuit board with conductive paths on two opposite sides of the board with the paths inductively and capacitively coupled

ABSTRACT

Communications jacks include a housing having a plug aperture that is configured to receive a mating RJ-45 plug along a longitudinal axis and eight jackwire contacts that are arranged as four differential pairs of jackwire contacts, each of the jackwire contacts including a plug contact region that extends into the plug aperture. A first of the jackwire contacts is configured to engage a longitudinally extending surface of a first blade of a mating RJ-45 plug when the mating RJ-45 plug is fully received within the plug aperture.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §120 as acontinuation of U.S. patent application Ser. No. 14/592,006, filed Jan.8, 2015, which in turn claims priority under 35 U.S.C. §120 as acontinuation of U.S. patent application Ser. No. 13/802,840, filed Mar.14, 2013, which in turn claims priority from 35 U.S.C. §119(e) from U.S.Provisional Patent Application Ser. No. 61/699,903, filed Sep. 12, 2012and to U.S. Provisional Patent Application Ser. No. 61/697,955, filedSep. 7, 2012. The disclosure of each of the above-referenced applicationis hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to communications connectorsand, more particularly, to communications jacks.

BACKGROUND

Computers, fax machines, printers and other electronic devices areroutinely connected by communications cables to network equipment suchas routers, switches, servers and the like. FIG. 1 illustrates themanner in which a computer 10 may be connected to a network device 30(e.g., a network switch) using conventional communications plug/jackconnections. As shown in FIG. 1, the computer 10 is connected by a patchcord 11 to a communications jack 20 that is mounted in a wall plate 18.The patch cord 11 comprises a communications cable 12 that contains aplurality of individual conductors (e.g., eight insulated copper wires)and first and second communications plugs 13, 14 that are attached tothe respective ends of the cable 12. The first communications plug 13 isinserted into a plug aperture of a communications jack (not shown) thatis provided in the computer 10, and the second communications plug 14 isinserted into a plug aperture 22 in the front side of the communicationsjack 20. The contacts or “blades” of the second communications plug 14are exposed through the slots 15 on the top and front surfaces of thesecond communications plug 14 and mate with respective “jackwire”contacts of the communications jack 20. The blades of the firstcommunications plug 13 similarly mate with respective jackwire contactsof the communications jack (not shown) that is provided in the computer10.

The communications jack 20 includes a back-end wire connection assembly24 that receives and holds insulated conductors from a cable 26. Asshown in FIG. 1, each conductor of cable 26 is individually pressed intoa respective one of a plurality of slots provided in the back-end wireconnection assembly 24 to establish mechanical and electrical connectionbetween each conductor of cable 26 and a respective one of a pluralityof conductive paths (not shown in FIG. 1) through the communicationsjack 20. The other end of each conductor in cable 26 may be connectedto, for example, the network device 30. The wall plate 18 is typicallymounted on a wall (not shown) of a room of, for example, an officebuilding, and the cable 26 typically runs through conduits in the wallsand/or ceilings of the office building to a room in which the networkdevice 30 is located. The patch cord 11, the communications jack 20 andthe cable 26 provide a plurality of signal transmission paths over whichinformation signals may be communicated between the computer 10 and thenetwork device 30. It will be appreciated that typically one or morepatch panels, along with additional communications cabling, would beincluded in the communications path between the cable 26 and the networkdevice 30. However, for ease of description, in FIG. 1 the cable 26 isshown as being directly connected to the network device 30.

In the above-described communications system, the information signalsthat are transmitted between the computer 10 and the network device 30are typically transmitted over a pair of conductors (hereinafter a“differential pair” or simply a “pair”) rather than over a singleconductor. An information signal is transmitted over a differential pairby transmitting signals on each conductor of the pair that have equalmagnitudes, but opposite phases, where the signals transmitted on thetwo conductors of the pair are selected such that the information signalis the voltage difference between the two transmitted signals. The useof differential signaling can greatly reduce the impact of noise on theinformation signal.

Various industry standards, such as the TIA/EIA-568-B.2-1 standardapproved Jun. 20, 2002 by the Telecommunications Industry Association,have been promulgated that specify configurations, interfaces,performance levels and the like that help ensure that jacks, plugs andcables that are produced by different manufacturers will all worktogether. By way of example, the TIA/EIA-568-C.2 standard (August 2009)is designed to ensure that plugs, jacks and cable segments that complywith the standard will provide certain minimum levels of performance forsignals transmitted at frequencies of up to 500 MHz. Most of theseindustry standards specify that each jack, plug and cable segment in acommunications system must include eight conductors 1-8 that arearranged as four differential pairs of conductors. The industrystandards specify that, in at least the connection region where thecontacts (blades) of a plug mate with the jackwire contacts of the jack(referred to herein as the “plug jack mating region”), the eightcontacts in the plug are generally aligned in a row, as are thecorresponding eight contacts in the jack. As shown in FIG. 2, whichschematically illustrates the positions of the jackwire contacts of ajack in the plug jack mating region, under the widely used TIA/EIA 568type B configuration, in which conductors 4 and 5 comprise differentialpair 1, conductors 1 and 2 comprise differential pair 2, conductors 3and 6 comprise differential pair 3, and conductors 7 and 8 comprisedifferential pair 4. As known to those of skill in the art, conductors1, 3, 5 and 7 comprise “tip” conductors, and conductors 2, 4, 6 and 8comprise “ring” conductors.

Unfortunately, the industry-standardized configuration for the plug-jackmating region that is shown in FIG. 2, which was adopted many years ago,generates a type of noise known as “crosstalk.” As is known to those ofskill in this art, “crosstalk” refers to unwanted signal energy that isinduced onto the conductors of a first “victim” differential pair from asignal that is transmitted over a second “disturbing” differential pair.The induced crosstalk may include both near-end crosstalk (NEXT), whichis the crosstalk measured at an input location corresponding to a sourceat the same location (i.e., crosstalk whose induced voltage signaltravels in an opposite direction to that of an originating, disturbingsignal in a different path), and far-end crosstalk (FEXT), which is thecrosstalk measured at the output location corresponding to a source atthe input location (i.e., crosstalk whose signal travels in the samedirection as the disturbing signal in the different path). Both types ofcrosstalk comprise an undesirable noise signal that interferes with theinformation signal on the victim differential pair.

Various techniques have been developed for cancelling out the crosstalkthat arises in industry standardized plugs and jacks. Many of thesetechniques involve providing crosstalk compensation circuits in eachcommunications jack that introduce “compensating” crosstalk that cancelsout much of the “offending” crosstalk that is introduced in the plug andthe plug-jack mating region due to the industry-standardized plug jackinterface. In order to achieve high levels of crosstalk cancellation,the industry standards specify small, pre-defined ranges for thecrosstalk that is injected between the four differential pairs in eachcommunication plug, which allows each manufacturer to design thecrosstalk compensation circuits in their communications jacks to cancelout these pre-defined amounts of crosstalk.

Unfortunately, due to the industry-standardized plug jack interface,there generally is a spatial separation, and hence a corresponding timedelay, between the region where the offending crosstalk is injectedbetween conductive paths of the mated plug and jack and the region wherethe compensating crosstalk is injected. As hard-wired communicationssystems move to higher frequency signals (as is necessary to supporthigher data rate communications), this delay degrades the effectivenessof conventional crosstalk compensation schemes. In particular,conventional crosstalk compensation schemes couple signal energy from asecond conductor of a disturbing differential pair onto a victimdifferential pair in order to cancel out the offending crosstalk that isgenerated when the first conductor of the disturbing differential paircouples energy onto the victim differential pair (e.g., in the plug jackmating region). This compensation scheme works because the signalscarried by the two conductors of the disturbing differential pair arephase-shifted by 180 degrees, and hence the signal energy coupled fromthe second conductor of the disturbing differential pair may be used tocancel out the signal energy coupled from the first conductor of thedisturbing differential pair. However, because of the time delay betweenthe points where the offending and compensating crosstalk signals areinjected onto the victim differential pair, a phase shift will occur inthe signal such that the offending and compensating crosstalk signalsare not quite 180 degrees separated in phase. When higher frequencysignals are used, the amount of this phase shift can become significant,which degrades the effectiveness of the crosstalk compensation.

In order to address the problem of phase shift at higher frequencies,so-called “multi-stage” crosstalk compensation schemes were developed,as disclosed, for example, in U.S. Pat. No. 5,997,358 to Adriaenssens etal. (hereinafter “the '358 patent”). Most high performancecommunications jacks that are in use today employ “multi-stage”crosstalk compensation circuits. With multi-stage crosstalkcompensation, a first stage of “compensating” crosstalk may be provided(which has a polarity that is opposite the polarity of the offendingcrosstalk) that not only compensates for the offending crosstalk, but infact over-compensates. Then, a second stage of compensating crosstalk isprovided that has the same polarity as the offending crosstalk thatcancels out the overcompensating portion of the first stage ofcompensating crosstalk. As explained in the '358 patent, the entirecontent of which is hereby incorporated herein by reference as if setforth fully herein, these multi-stage compensating schemes cantheoretically completely cancel an offending crosstalk signal at aspecific frequency and can provide significantly improved crosstalkcancellation over a range of frequencies.

SUMMARY

Pursuant to embodiments of the present invention, RJ-45 communicationsjacks are provided that have a housing having a plug aperture that isconfigured to receive a mating RJ-45 plug along a longitudinal axis ofthe jack. These jacks further include eight jackwire contacts that arearranged as four differential pairs of jackwire contacts, each of thejackwire contacts including a plug contact region that extends into theplug aperture. A first of the jackwire contacts is configured to engagea longitudinally extending surface of a first blade of a mating RJ-45plug when the mating RJ-45 plug is fully received within the plugaperture.

In some embodiments, a second of the jackwire contacts may also beconfigured to engage a longitudinally extending surface of a secondblade of the mating RJ-45 plug when the mating RJ-45 plug is fullyreceived within the plug aperture. In such embodiments, the firstjackwire contact may engage the longitudinal surface of the first bladeof the mating RJ-45 plug at a first distance from a plane defined by afront opening of the plug aperture, and the second jackwire contact mayengage the longitudinal surface of the second blade of the mating RJ-45plug at a second distance from the plane defined by the front opening ofthe plug aperture, where the second distance exceeds the first distance.In some embodiments, the second distance may exceed the first distanceby at least 20 mils.

In some embodiments, a second of the jackwire contacts may be configuredto engage a curved surface of a second blade of the mating RJ-45 plugwhen the mating RJ-45 plug is fully received within the plug aperture.The curved surface may be a surface that connects a longitudinallyextending surface of the second blade to a front surface of the secondblade. Additionally, a second of the jackwire contacts may be configuredto engage a second blade of the mating RJ-45 plug when the mating RJ-45plug is fully received within the plug aperture, and first and second ofthe jackwire contacts may be offset longitudinally, transversely andvertically when the mating RJ-45 plug is fully received within the plugaperture.

In some embodiments, all eight jackwire contacts may be configured toengage respective longitudinal surfaces of their corresponding blades ofthe mating plug when the mating plug is fully received within the plugaperture. In such embodiments, a first subset of the jackwire contactsmay engage the longitudinal surfaces of their mating plug blades at afirst distance from a first plane defined by a front opening of the plugaperture, and a second subset of the jackwire contacts may engage thelongitudinal surfaces of their mating plug blades at a second distancefrom the first plane. The second distance may exceed the first distance.In some embodiments, all of the tip jackwire contacts may be at the samedistance from the first plane, and all of the ring jackwire contacts maybe at the same distance from the first plane.

In some embodiments, each of the jackwire contacts may be mounted toextend from a top surface of a printed circuit board, and the portion ofeach jackwire contact that is at a maximum height above a plane definedby the top surface of the printed circuit board may be the plug contactregion of the jackwire contact.

Pursuant to further embodiments of the present invention, RJ-45communications jacks are provided that include a housing having a plugaperture. These jacks further include first through eighth jackwirecontacts that are arranged into differential pairs according to theTIA/EIA 568 type B configuration. The plug contact regions of the firstand third differential pairs of jackwire contacts are staggered so thatthe third jackwire contact couples at least as much with the fifthjackwire contact as it does with the fourth jackwire contact.

In some embodiments, the plug contact regions of the first and thirddifferential pairs of jackwire contacts may also be staggered so thatthe sixth jackwire contact couples at least as much with the fourthjackwire contact as it does with the fifth jackwire contact. The first,third, fifth and seventh jackwire contacts may be substantially alignedin a first row, and the second, fourth, sixth and eighth jackwirecontacts may be substantially aligned in a second row that is offsetfrom the first row.

In some embodiments, the plug blade contact regions of at least half ofthe jackwire contacts may be configured to mate with a flat bottomportion of a respective plug blade of a mating RJ-45 plug when themating RJ-45 plug is fully received within the plug aperture. The jackmay also include a flexible printed circuit board that electricallyconnects each of the jackwire contacts to respective ones of firstthrough eighth output terminals of the jack. In such embodiments, eachjackwire contact may have a first end that is mounted in the flexibleprinted circuit board and a second end that is mounted in a mountingsubstrate.

Pursuant to additional embodiments of the present invention, RJ-45communications jacks are provided that include a housing having a plugaperture that is configured to receive a mating RJ-45 plug along alongitudinal axis of the jack. The jacks also include at least oneprinted circuit board and first through eighth jackwire contacts thatare arranged into differential pairs according to the TIA/EIA 568 type Bconfiguration. Each jackwire contact has a first end and a second end,and both the first ends and the second ends of at least some of thejackwire contacts are mounted in the at least one printed circuit board.Additionally, the jackwire contacts are mounted in at least twotransverse rows across the plug aperture.

In some embodiments, the first, third, fifth and seventh jackwirecontacts may be substantially aligned in a first row, and the second,fourth, sixth and eighth jackwire contacts may be substantially alignedin a second row that is longitudinally offset from the first row. One ofthe jackwire contacts may be designed to inject a first signal that istransmitted from the RJ-45 communications jack into a mating RJ-45 plugat a first location that is a first distance from a front surface of themating RJ-45 plug while another of the jackwire contacts may be designedto inject a second signal that is transmitted from the RJ-45communications jack into a mating RJ-45 plug at a second location thatis a second distance from the front surface of the mating RJ-45 plug,where the first distance exceeds the second distance by at least 10mils.

In some embodiments, the at least one printed circuit board may be aflexible printed circuit board. The jackwire contacts of the first andthird differential pairs may be crosstalk neutral or introducecompensating crosstalk that has a polarity opposite the polarity of anoffending crosstalk that is generated between the plug blades of thefirst and third differential pairs of a mating RJ-45 plug. The at leastone printed circuit board may include a first flexible printed circuitboard and a second printed circuit board, and the first end of each ofthe jackwire contacts may be mounted in the first flexible printedcircuit board and the second end of at least some of the jackwirecontacts may be mounted in the second printed circuit board. In otherembodiments, a single flexible printed circuit board may be provided,and both ends of each of the jackwire contacts (or at least some ofthem) may be mounted in this flexible printed circuit board.

Pursuant to yet additional embodiments of the present invention,communications jacks are provided that include a housing, a printedcircuit board that is at least partially mounted within the housing, aplurality of jackwire contacts and a flexible printed circuit board thatis mounted on at least two of the jackwire contacts, the flexibleprinted circuit board including at least one crosstalk compensationcircuit. The plug contact surfaces of a first subset of the jackwirecontacts are substantially aligned in a first transverse row, and theplug contact surfaces of a second subset of the jackwire contacts aresubstantially aligned in a second transverse row that is offset from thefirst transverse row.

In some embodiments, the flexible printed circuit board may comprise afirst flexible printed circuit board, and the printed circuit board maycomprise a second flexible printed circuit board. In some embodiments,the first flexible printed circuit board may include a fold and/or aslit. The jackwire contacts may include first through eighth jackwirecontacts that are arranged into differential pairs according to theTIA/EIA 568 type B configuration. In such embodiments, the at least onecrosstalk compensation circuit may comprise at least one capacitor thatis coupled between the third jackwire contact and the fifth jackwirecontact. The jack may further include a third flexible printed circuitboard that is mounted on the fourth jackwire contact and the sixthjackwire contact, the third flexible printed circuit board including asecond crosstalk compensation circuit that comprises at least onecapacitor coupled between the fourth jackwire contact and the sixthjackwire contact. The first flexible printed circuit board may bemounted to a portion of the at least two jackwire contacts that are onopposite sides of the contacts from the plug contact surfaces thereof.

Pursuant to yet additional embodiments of the present invention,communications jacks are provided that include a housing having a plugaperture, a plurality of jackwire contacts that each have a plug contactsurface that is exposed within the plug aperture, and a flexible printedcircuit board that is mounted on first and second of the jackwirecontacts opposite the plug contact surfaces of the first and second ofthe jackwire contacts. The flexible printed circuit board includes atleast one crosstalk compensation circuit, and also includes at least onefold and/or slit.

Pursuant to still further embodiments of the present invention,communications jacks are provided that include a plurality of inputcontacts, a plurality of output contacts and a plurality of conductivepaths that each electrically connect a respective one of the inputcontacts to a respective one of the output contacts, the conductivepaths being arranged as a plurality of differential pairs of conductivepaths. These jacks further include a first crosstalk compensation stagethat is provided between first and second of the differential pairs ofconductive paths, the first crosstalk compensation stage configured toinject crosstalk having a first polarity between the first and second ofthe differential pairs of conductive paths. The jacks further include asecond crosstalk compensation stage that is provided between the firstand second of the differential pairs of conductive paths, the secondcrosstalk compensation stage including an inductive sub-stage that isconfigured to inject inductive crosstalk having the first polaritybetween the first and second of the differential pairs of conductivepaths and a capacitive sub-stage that is configured to inject capacitivecrosstalk having a second polarity between the first and second of thedifferential pairs of conductive paths, the second polarity beingopposite the first polarity. The capacitive sub-stage is a distributedcapacitive sub-stage.

In some embodiments, the capacitive sub-stage and the inductivesub-stage may inject substantially the same amount of crosstalk as afunction of time so as to be substantially self-cancelling atfrequencies up to 2 GHz. The second crosstalk compensation stage maycomprise a first trace of the first differential pair on a first side ofa flexible printed circuit board and a second trace of the seconddifferential pair on a second side of the flexible printed circuit boardthat at least partially overlaps the first trace. At least one of thefirst trace or the second trace may be a widened trace that isconfigured to have increased capacitive coupling with the other of thefirst trace or the second trace. The first trace may only partiallyoverlap the second trace, and the degree of overlap may be selected tomatch the amounts of inductive and capacitive crosstalk injected in thesecond stage. The second crosstalk compensation stage may be formed byboth inductively and capacitively coupling a tip conductive path of thefirst differential pair of conductive paths and a ring conductive pathof the second differential pair of conductive paths. In suchembodiments, the inductively and capacitively coupled portions of thetip conductive path of the first differential pair of conductive pathsand the ring conductive path of the second differential pair ofconductive paths may be mounted on opposite sides of a flexible printedcircuit board.

Pursuant to additional embodiments of the present invention, RJ-45communications jacks are provided that include eight inputs, eightoutputs and eight conductive paths that connect the eight inputs to therespective eight outputs, where the conductive paths are arranged intodifferential pairs according to the TIA/EIA 568 type B configuration.These jacks further include a first crosstalk compensation stage thatcomprises at least a first capacitor that is coupled between either thethird conductive path and the fourth conductive path or between thefifth conductive path and the sixth conductive path, and a secondcrosstalk compensation stage that comprises at least an inductivecoupling section between either the third conductive path and the fourthconductive path or between the fifth conductive path and the sixthconductive path. The first capacitor is a distributed capacitor thatinjects capacitance at multiple locations between the first and thirddifferential pairs of conductive paths, and the first and secondcompensating stages substantially cancel one another.

In some embodiments, the jacks further include a third crosstalkcompensation stage that is configured to cancel crosstalk introducedbetween the first and third differential pairs of conductive paths in amating RJ-45 plug and any crosstalk injected between the first and thirddifferential pairs of conductive paths at the plug jack interface. Theconductive paths may be at least partly implemented on a flexibleprinted circuit board, and the inductive coupling section may comprise afirst trace section on a first side of the flexible printed circuitboard that inductively couples with a second trace section on theopposite side of the flexible printed circuit board. In suchembodiments, the first and second trace sections may partly overlap butnot completely overlap. The third crosstalk compensation stage may belocated closer to the plug jack mating point than are the first andsecond crosstalk compensation stages.

Pursuant to further embodiments of the present invention, communicationsjacks are provided that include a plurality of input contacts, aplurality of output contacts and a plurality of conductive paths thateach electrically connect a respective one of the input contacts to arespective one of the output contacts, the conductive paths beingarranged as a plurality of differential pairs of conductive paths thateach have a tip conductive path and a ring conductive path. A firstcrosstalk compensation stage is provided between first and second of thedifferential pairs of conductive paths, the first crosstalk compensationstage being configured to inject crosstalk having a first polaritybetween the first and second of the differential pairs of conductivepaths. A second crosstalk compensation stage is also provided thatcomprises at least first and second coupling trace sections that areprovided on opposite sides of a flexible printed circuit board, wherethe first and second coupling trace sections are configured to generatea first amount of inductive coupling per unit length and a second amountof capacitive coupling per unit length of the opposite polarity thereto.

In some embodiments, the first amount of inductive coupling per unitlength and the second amount of capacitive coupling per unit length maybe substantially equal. The first and second trace sections may partlyoverlap but not completely overlap. The first trace section may be partof a tip conductive path and the second trace section may be part of aring conductive path. The first crosstalk compensation stage may beconfigured to cancel crosstalk introduced between the first and secondof the differential pairs of conductive paths in a mating plug and anycrosstalk injected between the first and second of the differentialpairs of conductive paths at an interface of the mated plug and jack.The first crosstalk compensation stage may be located closer in time tothe interface with the mated plug than is the second crosstalkcompensation stage.

Pursuant to other embodiments, RJ-45 communications jacks are providedthat include a housing having a plug aperture, at least one printedcircuit board and first through eighth jackwire contacts that arearranged into differential pairs according to the TIA/EIA 568 type Bconfiguration. Each of the jackwire contact has a first end that ispositioned forwardly in the housing and a second end that is positionedrearward of the first end, and both the first ends and the second endsof at least some of the jackwire contacts are mounted in the at leastone printed circuit board. Moreover, the signal current carrying paththrough at least one of the first through eighth jackwire contactspasses through the first end thereof while the signal current carryingpath through at least another of the jackwire contacts passes throughthe second end thereof.

In some embodiments, the signal current-carrying path for each of thefirst, third, fifth and seventh jackwire contacts may extend in a firstdirection from the plug blade contact regions thereof and the signalcurrent-carrying path for each of the second, fourth, sixth and eighthjackwire contacts may extend in a second direction from the plug bladecontact regions thereof, the second direction being generally oppositethe first direction. The at least one printed circuit board may be aflexible printed circuit board.

In some embodiments, the jacks may be configured so that variations inthe amount of offending crosstalk generated between a first differentialpair of jackwire contacts and a third differential pair of jackwirecontacts based on a plug penetration depth of a mating plug into theplug aperture when the mating plug is latched into place within the plugaperture is offset by substantially equal and opposite changes in theamount of compensating crosstalk injected in the mated plug jackcombination between the first and third differential pairs of jackwirecontacts.

Pursuant to still further embodiments of the present invention,communications jacks are provided that include at least four conductivepaths that electrically connect four inputs of the jack to respectiveones of four outputs of the jack, where the first and second conductivepaths comprise a first differential pair and the third and fourthconductive paths comprise a second differential pair. These jacksfurther include a return loss improvement circuit that comprises a firstsection of the first conductive path and a second section of the secondconductive path that has the same instantaneous current direction as thefirst section of the first conductive path, where the first and secondsections are positioned to both capacitively and inductively couple witheach other.

In some embodiments, the amount of capacitive coupling is at least halfthe amount of the inductive coupling. The jack may also include aflexible printed circuit board, and the first section of the firstconductive path may be on a first side of the flexible printed circuitboard and the second section of the second conductive path may be on asecond side of the flexible printed circuit board that is opposite thefirst side. The ratio of the capacitive coupling to the inductivecoupling in the return loss improvement circuit may be selected toprovide a local maximum in a return loss spectrum. Moreover, the jackmay include a second return loss improvement circuit that comprises athird section of the third conductive path and a fourth section of thefourth conductive path that has the same instantaneous current directionas the third section of the third conductive path, where the thirdsection and the fourth section are positioned to both capacitively andinductively couple with each other.

Pursuant to yet other embodiments of the present invention, methods ofcontrolling the return loss on a differential transmission line thatincludes a first conductive path and a second conductive path of anRJ-45 communications connector are provided in which a first section ofthe first conductive path and a first section of the second conductivepath are routed so that the first and second sections have substantiallythe same instantaneous current direction and so that the first andsecond sections both capacitively and inductively couple with oneanother. The amounts of capacitive and inductive coupling between thefirst and second sections are then controlled to improve the return lossof the transmission line.

In some embodiments, controlling the amounts of capacitive and inductivecoupling comprises selecting the amounts of capacitive and inductivecoupling to create a resonance that generates a local maximum in thereturn loss spectrum within twice the operating frequency range of thecommunications jack. The first section may be on a first side of aflexible printed circuit board and the second section may be on a secondside of the flexible printed circuit board that is opposite the firstside. The first and second sections may at least partially overlap. Insome embodiments, the first section may be a widened conductive tracethat both inductively and capacitively couples through the flexibleprinted circuit board with a conductive trace that forms the secondsection. The amounts of capacitive and inductive coupling between thefirst and second sections may be controlled to improve the return lossof the transmission line by selecting widths for first and secondconductive traces that are used to form the first and second sectionsand/or selecting a degree to which the first and second conductivetraces overlap and/or a length of the overlapping sections of the firstand second conductive traces.

Pursuant to further embodiments of the present invention, communicationsjacks are provided that include a housing having a plug aperture, aflexible printed circuit board that is at least partly mounted withinthe housing, a first conductive path electrically connecting a firstinput of the jack and a first output of the jack, and a secondconductive path electrically connecting a second input of the jack and asecond output of the jack, where the first and second conductive pathscomprise a first differential pair of conductive paths. The firstconductive path includes first and second conductive trace sections onthe flexible printed circuit board that are immediately adjacent to eachother and that have generally the same instantaneous current directionsuch that the first and second conductive trace sections self-couple andcause a localized increase in inductance. The first conductive tracesection is on a first side of the flexible printed circuit board and thesecond conductive trace section is on a second side of the flexibleprinted circuit board that is opposite the first side. The first andsecond conductive trace sections are configured to both inductively andcapacitively couple into each other.

In some embodiments, at least one of the conductive trace sectionscomprises a spiral. The first conductive trace section may at leastpartially overlap the second conductive trace section. An amount ofcapacitive coupling between the first and second conductive tracesections may be at least half an amount of inductive coupling betweenthe first and second conductive trace sections.

Pursuant to still further embodiments of the present invention, RJ-45communications jacks are provided that have a housing having a plugaperture that is configured to receive a mating RJ-45 plug along alongitudinal axis of the jack. The jacks also include a flexible printedcircuit board having a first conductive path and a second conductivepath that form a first differential pair of conductive paths and a thirdconductive path and a fourth conductive path that form a seconddifferential pair of conductive paths. First through fourth jackwirecontacts are electrically connected to the respective first throughfourth conductive paths. A section of the first conductive path is on afirst side of the flexible printed circuit board and a section of thethird conductive path is on a second side of the flexible printedcircuit board that is opposite the first side, and the section of thefirst conductive path and the section of the third conductive path areconfigured to form a coupling section in which the first and thirdconductive paths both inductively and capacitively couple.

In some embodiments, the section of the first conductive path and thesection of the third conductive path that form the coupling sectionpartially overlap but do not completely overlap. A first end of thecoupling section and an intercept between the first jackwire contact andthe first side of the flexible printed circuit board may besubstantially transversely aligned. A first end of the coupling sectionand an intercept between the third jackwire contact and the second sideof the flexible printed circuit board may be substantially transverselyaligned. An intercept between the first jackwire contact and the firstconductive path on the first side of the flexible printed circuit boardand an intercept between the third jackwire contact and the thirdconductive path on the second side of the flexible printed circuit boardmay be substantially equidistant from a plane defined by a front openingof the plug aperture.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic drawing that illustrates the use of communicationsplug and jack connectors to connect a computer to a network device.

FIG. 2 is a schematic diagram illustrating the TIA 568 type B modularjack contact wiring assignments for a conventional 8-positioncommunications jack as viewed from the front opening of the jack.

FIG. 3 is a perspective view of a communications jack according toembodiments of the present invention.

FIG. 4 is a schematic perspective view of a portion of a communicationsinsert of the communications jack of FIG. 3.

FIG. 5 is a side view of one of the jackwire contacts of thecommunications insert of FIG. 4.

FIG. 6 is a schematic side cross-sectional view of the front portion ofthe communications insert of FIG. 4 taken along the longitudinal lengthof one of the jackwire contacts.

FIG. 6A is a schematic side cross-sectional view of the front portion ofa modified version of the communications insert of FIG. 4 taken alongthe longitudinal length of one of the jackwire contacts.

FIG. 7 is a perspective view of the rear portion of the jack of FIG. 3with the terminal housing removed to expose the output terminals of thejack.

FIG. 8 is a schematic plan view of a flexible printed circuit board ofthe communications insert of FIG. 4.

FIG. 9 is a schematic plan view of a spring of the communications insertof FIG. 4.

FIG. 10 is a schematic perspective view of a portion of a communicationsinsert for a communications jack according to further embodiments of thepresent invention.

FIG. 11 is a schematic plan view of the jackwire contact mountedflexible printed circuit board of the communications insert of FIG. 10.

FIG. 11A is a schematic plan view of a modified version of the flexibleprinted circuit board of FIG. 11.

FIG. 12 is a schematic perspective view of a portion of a communicationsinsert for a communications jack according to still further embodimentsof the present invention.

FIG. 13 is a schematic perspective view of a portion of a communicationsinsert for a communications jack according to yet additional embodimentsof the present invention.

FIG. 14 is a vector diagram illustrating a crosstalk compensation schemefor cancelling both NEXT and FEXT according to embodiments of thepresent invention.

FIG. 15 is a schematic plan view of a flexible printed circuit board ofa communications insert that implements the compensation scheme of FIG.14.

FIG. 16 is a schematic plan view of a flexible printed circuit board ofa communications insert according to further embodiments of the presentinvention.

FIG. 17 is a schematic plan view of a flexible printed circuit board ofa communications insert according to still further embodiments of thepresent invention.

FIG. 18 is a schematic plan view of a flexible printed circuit board ofa communications insert according to yet additional embodiments of thepresent invention.

FIG. 18A is a schematic plan view of the traces of a differentialtransmission line illustrating how parallel trace sections having thesame instantaneous current direction may be used to generate a localizedincrease in inductance.

FIG. 18B is a schematic plan view illustrating how the trace sections ofFIG. 18B need not be perfectly parallel to generate the localizedincrease in inductance.

FIG. 19 is a schematic plan view of a flexible printed circuit board ofa communications insert according to even further embodiments of thepresent invention.

FIG. 19A is a schematic graph that illustrates how the relative amountsof inductive and capacitive self-coupling may be tuned to generate alocal maximum in the return loss spectrum for a differentialtransmission line according to embodiments of the present invention.

FIG. 20 is a schematic plan view of a flexible printed circuit board ofa communications insert according to still further embodiments of thepresent invention.

FIG. 21 is a schematic plan view of a flexible printed circuit board ofa communications insert according to yet additional embodiments of thepresent invention.

DETAILED DESCRIPTION

Pursuant to embodiments of the present invention, communications jacksare provided that may operate at very high frequencies (e.g.,frequencies of 1-2 GHz or more) while exhibiting good crosstalkcancellation and return loss performance.

In some embodiments, the communications jacks include a plurality ofjackwire contacts that are electrically connected to a flexible printedcircuit board. The jackwire contacts (which may also be referred toherein as a “leadframe”) may be designed to reduce or minimize theamount of offending crosstalk that is generated within the leadframe.Generally speaking, the less offending crosstalk that is generated thebetter the performance of the jack, given the difficulty of perfectlycancelling such offending crosstalk. In some embodiments, the jackwirecontacts may be arranged in a staggered fashion such that the jackwirecontacts are disposed in two or more transverse rows. This stagger mayreduce the amount of offending crosstalk that is generated in the plugcontact regions of the jackwire contacts. In fact, in some embodiments,the stagger may be sufficiently pronounced that the leadframe may be“neutral” (i.e., does not generate any crosstalk between twodifferential pairs), or may even be compensating (i.e., does notgenerate any crosstalk between two differential pairs and also generatesat least some compensating crosstalk between the two pairs). Forexample, according to embodiments of the present invention, RJ-45 jacksmay be provided that are neutral or even compensating with respect tocrosstalk between pairs 1 and 3 (specific references to pairs 1, 2, 3and 4 herein are to pairs 1 through 4 as defined by the TIA/EIA type568B configuration, while references to a “first pair”, “second pair”,etc. may be to any pair and need not necessarily refer to a pair of anindustry standards compliant connector). As discussed above, this paircombination may have the most severe crosstalk issues.

In some embodiments, the staggered jackwire contacts may be designed toengage the bottom (longitudinal) surface of the respective blades of amating plug as opposed to the curved transition sections of the plugblades that connect the front surface and bottom surface of each plugblade. As a result, the stagger in the jackwire contacts may bemaintained even when a plug is fully received within the plug apertureof the jack. This may facilitate providing a leadframe that generateslittle or no additional offending crosstalk.

In some embodiments, the communications jacks may include first stagecrosstalk compensation circuits that inject compensating crosstalksignals at a very small delay from the plug jack mating point. Thesefirst stage crosstalk compensation circuits may be attached, forexample, to non-signal current carrying ends of the jackwire contacts ormay be attached to a printed circuit board that is mounted on thejackwire contacts substantially directly under the plug blade contactregions. By injecting first stage compensating crosstalk signals verynear the plug-jack mating point improved crosstalk cancellation may beachieved.

In some embodiments, single stage crosstalk compensation schemes may beused that further include a “transparent” second stage of crosstalkcompensation. This transparent second stage may include inductivecrosstalk having a first polarity and capacitive crosstalk that has asecond polarity. The inductive and capacitive crosstalk components ofthe second stage may be injected at the same locations such that theysubstantially cancel each other out. In this manner, the ratio ofinductive to capacitive crosstalk included in the crosstalk compensationcircuitry may be adjusted, which allows optimization of both the NEXTand FEXT cancellation in the jack. In some embodiments, the transparentsecond stage of crosstalk compensation may be implemented as overlappingtraces on opposite sides of a flexible printed circuit board thatgenerate inductive crosstalk having a first polarity and capacitivecrosstalk having a second polarity.

In some embodiments, the “signal current carrying path” through at leastsome of the jackwire contacts may flow in a different direction than thesignal current carrying path through other of the jackwire contacts.Herein, the term “signal current carrying path” refers to the shortestphysical path that a communications signal travels along a structure(e.g., a jackwire contact) when the signal passes through the structureon the way to its destination. For example, in some embodiments of RJ-45jacks, the signal current carrying paths through the jackwire contactsfor pair 3 may flow in a first direction while the signal currentcarrying paths through the remaining jackwire contacts may flow in asecond, different direction. In other embodiments, the signal currentcarrying paths through the tip jackwire contacts may flow in a firstdirection while the signal current carrying paths through the ringjackwire contacts may flow in the second direction.

In some embodiments, various techniques may be used to improve thereturn loss of the differential transmission lines through the jack. Forexample, in some embodiments, the differential transmission lines may beconfigured so that the two conductors thereof both inductively andcapacitively couple. These couplings may create resonances, and theresonances may be selected so that the return loss of the transmissionline may be improved in a selected frequency range. In otherembodiments, one or both conductors of a differential transmission linemay be arranged so as to self-couple both inductively and capacitivelyto generate such resonances. High amounts of inductive and capacitivecoupling may be generated by running the two traces of a differentialpair (or a single trace that self-couples) on opposite sides of aflexible printed circuit board.

In some embodiments, high levels of inductive crosstalk compensation maybe provided by routing the traces associated with two differentdifferential pairs on opposite sides of a flexible printed circuit boardin an overlapping arrangement. As the dielectric layer of flexibleprinted circuit boards may be very thin (e.g., 1 mil), very high amountsof inductive crosstalk compensation may be achieved in a very shortdistance. This may also facilitate moving the crosstalk compensation inthe jack closer to the plug jack mating point which, as discussed above,may often improve the crosstalk cancellation capabilities of the jack.

As discussed above, the present invention is primarily directed tocommunications jacks. As used herein, the terms “forward” and “front”and derivatives thereof refer to the direction defined by a vectorextending from the center of the jack toward a plug aperture of thejack. The term “rearward” and derivatives thereof refer to the directiondirectly opposite the forward direction. The forward and rearwarddirections define the longitudinal dimension of the jack. The vectorsextending from the center of the jack toward the respective sidewalls ofthe jack housing defines the transverse dimension of the jack. For RJ-45jacks, the blades of an RJ-45 plug that is received within the plugaperture are aligned in a row along the transverse dimension. Thetransverse dimension is normal to the longitudinal dimension. Thevectors extending from the center of the jack toward the respective topand bottom walls of the jack housing defines the vertical dimension ofthe jack. The vertical dimension of the jack is normal to both thelongitudinal and transverse dimensions.

The communications jacks according to embodiments of the presentinvention may comprise, for example, RJ-45 or RJ-11 jacks, althoughembodiments of the present invention are not limited thereto.

Embodiments of the present invention will now be described withreference to the accompanying drawings, in which example embodiments areshown. Herein, when the communications jacks according to embodiments ofthe present invention include multiple of the same components, thesecomponents may be referred to individually by their full referencenumerals (e.g., jackwire contact 140-4) and may be referred tocollectively by the first part of their reference numeral (e.g., thejackwire contacts 140).

FIG. 3 is a perspective view of a communications jack 100 according toembodiments of the present invention. FIG. 4 is a schematic perspectiveview of a portion of a communications insert 120 for the communicationsjack 100. FIG. 5 is a side view of one of the jackwire contacts of thecommunications insert 120. FIG. 6 is a schematic side cross-sectionalview of the front portion of the communications insert 120 taken alongthe longitudinal length of one of the jackwire contacts thereof. FIG. 7is a perspective view of the rear portion of the jack 100 with theterminal housing removed to expose the output terminals of the jack.FIG. 8 is a schematic plan view of a flexible printed circuit board thatis part of the communications insert 120. Finally, FIG. 9 is a schematicplan view of a spring of the communications insert of 120.

As shown in FIG. 3, the jack 100 includes a housing 110. In the depictedembodiment, the housing 110 includes a jack frame 112, a cover 116 and aterminal housing 118. The jack frame 112 includes a plug aperture 114for receiving a mating communications plug. The housing components 112,116, 118 may be conventionally formed and need not be described indetail herein. Those skilled in this art will recognize that otherconfigurations of jack frames, covers and terminal housings may also beemployed with the present invention, and that the housing 110 may havemore or fewer than three pieces. It will also be appreciated that thejack 100, when mounted for use, is typically rotated 180 degrees aboutits longitudinal axis from the orientation shown in FIG. 3. In FIG. 3,the x-axis extends in the longitudinal direction, the y-axis extends inthe transverse direction, and the z-axis extends in the verticaldirection. In the discussion that follows, the relationships of thecomponents of jack 100 with respect to each other will be described withrespect to the orientation illustrated in the figures for convenience.

FIG. 4 illustrates a portion of a communications insert 120 of the jack100. The forward portion of the communications insert 120 is receivedwithin an opening in the rear of the jack frame 112. The bottom of thecommunications insert 120 is protected by the cover 116, and the top ofthe communications insert 120 is covered and protected by the terminalhousing 118. The communications insert 120 further includes a flexibleprinted circuit board 130, a plurality of jackwire contacts 140, aplurality of dielectric contact carriers 150 (only dielectric contactcarrier 150-1 is visible in FIG. 4), a spring 160 (see FIG. 9) and aplurality of output contacts 170 (see FIG. 7), each of which will bediscussed in further detail below. A substrate 122 (see FIG. 6) may beprovided in some embodiments that may be disposed between the cover 116and the flexible printed circuit board 130. The output contacts 170 maybe mounted into both the flexible printed circuit board 130 and theunderlying substrate 122 which provides additional mechanical support.

As shown best in FIGS. 4, 6 and 8, the flexible printed circuit board130 may comprise an elongated printed circuit board that is formed of aflexible material that may be bent in various ways. The flexible printedcircuit board 130 may comprise a fully flexible printed circuit board ora so-called “rigid-flex” printed circuit board that includes bothflexible and rigid regions or sections. In the depicted embodiment, theflexible printed circuit board 130 includes a pair of longitudinal slots133 that “decouple” a front portion 131 of the flexible printed circuitboard 130 from the back portion 132. In particular, the slots 133 allowthe front portion 131 of the flexible printed circuit board 130 to bemoved within a range without substantially impacting the rear portion132, and vice versa. As shown in FIG. 6, the slots 133 allow the frontportion 131 of flexible printed circuit board 130 to be disposed at alower level (vertically) within the jack housing 110 than the rearportion 132. The flexible printed circuit board 130 further includes alateral slot 134 that extends between the pair oflongitudinally-extending slots 133. While the communications insert 120includes a single flexible printed circuit board 130, it will beappreciated that in other embodiments two or more printed circuit boards(or other substrates) may be provided. For example, the front portion131 of the flexible printed circuit board 130 could be replaced with afirst flexible or non-flexible printed circuit board and the rearportion 132 of flexible printed circuit board 130 could be replaced witha second flexible printed circuit board in other embodiments of thepresent invention. In some embodiments, the flexible printed circuitboard 130 may be cut into two pieces (e.g., along the transverse slot134) and mounted within the jack housing as two separate flexibleprinted circuit boards.

The flexible printed circuit board 130 may include one or moredielectric layers that may have conductive traces and/or other elementsdisposed on one or both sides thereof, as is known to those of skill inthe art. The flexible printed circuit board 130 may be used as atransmission medium for signals that pass between the jackwire contacts140 and the respective output contacts 170 of the jack 100, as will beexplained in more detail with reference to FIG. 8. The flexible printedcircuit board 130 may also include a plurality of crosstalk compensationcircuits disposed thereon or therein, which will also be discussed inmore detail below with reference to FIG. 8.

As is further shown in FIGS. 4 and 8, a plurality of longitudinal slots135-1 through 135-7 are provided in the front portion 131 of theflexible printed circuit board 130 that define eight rearwardly facingfingers 136-1 through 136-8. Likewise, six longitudinal slots 137-1through 137-6 are provided in the rear portion 132 of the flexibleprinted circuit board 130 that define a plurality of additional fingers138-1 through 138-6. As shown in FIGS. 4 and 8, fingers 138-1, 138-2,138-5 and 138-6 are generally longitudinally-extending fingers that faceforwardly, while fingers 138-3 and 138-4 have both longitudinal andtransverse components. Herein, a “finger” on a substrate such as aflexible printed circuit board refers to a cantilevered portion of thesubstrate, regardless of the particular shape. Thus, it will beunderstood that the fingers 136, 138 need not be elongated fingers.

The eight fingers 136 may move relatively independent of each other suchthat each finger 136 may be depressed a different distance downwardlywhen the jack 100 is mated with a communications plug. Likewise, the sixfingers 138 may also move relatively independent of each other in thissituation. The ability of each finger 136, 138 to move relativelyindependent of the other fingers 136, 138 may improve the performanceand reliability of the jack 100.

In particular, various industry standards specify certain physicalcharacteristics that must be met for a communications plug to qualify asan industry-standardized communications plug. The physicalcharacteristics specified in these standards include the distances thatportions of the plug blades must be from the bottom and front surfacesof the plug housing (when the plug is oriented as shown in FIG. 6), andthe industry standards specify ranges for these distances to accommodatemanufacturing tolerances. Because ranges are specified, a communicationsplug may be industry-standard compliant even though its plug blades arenot all the same distance from the bottom and/or front surfaces of theplug housing (i.e., the blades may be offset from each other in thelongitudinal direction and/or the vertical direction).

When a communications plug that has plug blades that are offset fromeach other is inserted into the jack 100, certain of the plug blades mayengage their respective jackwire contacts 140 of jack 100 sooner thanother of the plug blades. The subset of the jackwire contacts 140 thatare initially engaged in this fashion exert a downward force on theflexible printed circuit board 130. If the flexible printed circuitboard 130 did not include the fingers 136, 138, as the flexible printedcircuit board 130 is pushed downwardly, it would draw the remainingjackwire contacts 140 downward as well (i.e., the jackwire contacts 140that had not yet been engaged by their respective plug blades), pullingthese jackwire contacts 140 away from their respective plug blades. As aresult, some of the jackwire contacts 140 will exert a greater contactforce against their respective plug blades (namely the jackwire contacts140 that are initially contacted by the offset plug blades) than willother of the jackwire contacts 140. If the flexible printed circuitboard 130 does not include the fingers 136, 138 this effect may bemagnified such that, under certain circumstances, some of the jackwirecontacts 140 may exhibit poor contact force (or even no contact force atall) against their respective plug blades. However, by providing thefingers 136, 138 on the flexible printed circuit board 130, the degreeto which the movement of a first of the jackwire contacts 140 changesthe position of other of the jackwire contacts 140 may be reduced, andhence the jack 100 may be less susceptible to performance degradationwhen used with plugs that have plug blades that are offset from eachother in the longitudinal and/or vertical directions.

As shown best in FIGS. 4-6, eight low coupling jackwire contacts 140-1through 140-8 are mounted in two rows on a top surface of the flexibleprinted circuit board 130. Herein, a “jackwire contact” refers to aconductive contact structure of the jack that is mounted in or on astructure so as to extend into the plug aperture of the jack. Eachjackwire contact 140 is configured to mate with a blade (or othercontact structure) of a communications plug that is received within theplug aperture 114 of the jack 100. As noted above, the jackwire contacts140 may be collectively referred to in some instances herein as a“leadframe.”

As shown in FIG. 5, each jackwire contact 140 has a first end 142, asecond end 146 and a middle section 144 that includes a “plug contactregion” (i.e., the portion of the jackwire contact 140 that engages theblade of a mating plug that is received within the plug aperture 114 ofjack 100). The jackwire contacts 140 may be formed of, for example, aresilient metal such as beryllium-copper or phosphor-bronze, or anon-resilient metal such as copper or gold-plated copper. In someembodiments, the jackwire contacts 140 may comprise substantially rigidcontacts, meaning that the jackwire contacts 140 do not flex more than ade minimis amount when engaged by the respective blades of a mating plugduring normal use of the jack 100. The first end 142 of each jackwirecontact 140 is mounted to extend upwardly from a respective one of thefingers 136. The first end 142 of each jackwire contact 140 may extendthrough a respective one of a plurality of metal-plated apertures 139-1through 139-8 that are provided in the fingers 136 (see FIG. 8). Thesecond end of each jackwire contact 140 is mounted to extend upwardlyfrom a respective one of the fingers 138. The second end 146 of eachjackwire contact 140 may extend through a respective one of a pluralityof metal-plated apertures 139-9 through 139-16 that are provided in thefingers 138 (see FIG. 8). The metal-plated apertures 139-1 through139-16 electrically connect each jackwire contact 140 to respectiveconductive traces or other structures on the flexible printed circuitboard 130, as will be discussed in more detail below with reference toFIG. 8.

The first end 142 and the second end 146 of each jackwire contact 140may each be mounted to be substantially perpendicular to a top surfaceof the flexible printed circuit board 130 (although they need not be).The middle portion 144 of each jackwire contact 140 may be raised abovethe top surface of the flexible printed circuit board 130 such that agap or spacing exists between a lower surface of the middle portion 144of each jackwire contact 140 and the upper surface of the flexibleprinted circuit board 130. Additionally, the middle portion 144 of eachjackwire contact 140 may define an oblique angle with respect to theplane or planes that are defined by the top surface of the flexibleprinted circuit board 130, as is shown in FIG. 6.

In some embodiments (such as the depicted embodiment), all of thejackwire contacts 140 may have the same profiles. This may simplify themanufacturing process and may also reduce production costs. However, inother embodiments the jackwire contacts 140 may have different profiles.For example, jackwire contacts 140-1, 140-3, 140-5 and 140-7 may have afirst profile, while jackwire contacts 140-2, 140-4, 140-6 and 140-8 mayhave a second profile that is different from the first profile. Thejackwire contact profiles may be designed to reduce coupling betweenadjacent jackwire contacts 140 by reducing the size of the region whereadjacent jackwire contacts 140 are close to each other.

As is shown in FIGS. 4 and 6, the communications insert 120 furtherincludes eight dielectric contact carriers 150-1 through 150-8. Herein,a “contact carrier” refers to a structure that provides mechanicalsupport to a jackwire contact. In the depicted embodiment, each contactcarrier 150 comprises an elongated, generally planar strip of moldedplastic. Each contact carrier 150 extends parallel to the longitudinalaxis of the jack 100, and each contact carrier 150 may be longitudinallyaligned with a respective one of the jackwire contacts 140. The contactcarriers 150 are aligned side-by-side in a row (in numerical order) inthe lateral direction. Each of the dielectric contact carriers 150includes an upwardly-extending protrusion 152. Each of these protrusions152 is aligned underneath a respective one of the fingers 138. The firstend 142 of each jackwire contact 140 extends through a respective one ofthe fingers 136 into an aperture in a top surface of the contact carrier150 that is positioned underneath the jackwire contact 140. The secondend 146 of each jackwire contact 140 extends through a respective one ofthe fingers 138 into an aperture on a respective one of the protrusions152 on the contact carrier 150 that is positioned underneath thejackwire contact 140. The protrusions 152 act to hold the lower surfaceof the flexible printed circuit board 130 above the main upper surfaceof the contact carriers 150 in order to allow the fingers 138 to morefreely flex downwardly when a mating plug is received within the plugaperture 114. While not shown in the figures, it will be appreciatedthat a second, identical, protrusion 152 may also be included on eachcontact carrier 150 directly underneath each respective finger 136, andthat the first end 142 of each respective jackwire contact 140 may bereceived in these respective second protrusions 152.

While only one of the dielectric contact carriers 150 (namely contactcarrier 150-1) is fully illustrated in FIGS. 4 and 6, it will beappreciated that all of the contact carriers 150-1 through 150-8 may beidentical except that the location of the protrusions 152 may beadjusted to be underneath the second end 146 of their mating jackwirecontact 140. While the contact carriers 150 are completely separate fromeach other in the depicted embodiment, it will be appreciated that inother embodiments some of the contact carriers 150 may be connected toeach other.

Each contact carrier 150 may be mounted to move within the jack 100, aswill be discussed in more detail below with respect to FIG. 9. As theends 142, 146 of each jackwire contact 140 are mounted in a respectiveone of the contact carriers 150, each dielectric contact carrier 150 andits respective jackwire contact 140 will move together as a single unitwhen a communications plug is inserted into the plug aperture 114 ofjack 100 and physically engages the jackwire contacts 140.

Referring to FIGS. 6 and 9, it can be seen that the communicationsinsert 120 further includes a spring 160. The spring 160 may comprise acomb-like structure that has a base 162 and eight fingers 164-1 through164-8. The spring 160 may be implemented, for example, as a piece ofresilient metal such as beryllium-copper or phosphor-bronze that ismounted, for example, to a bottom surface of the substrate 122 (oranother substrate or housing piece of the jack 100) by any appropriatemeans. However, it will be appreciated that a wide variety of differentmaterials may be used to form the spring 160, including other metals,plastics, etc., and it will also be appreciated that the spring 160 maybe implemented in many different forms (e.g., as a coiled spring, acantilevered spring, etc.). In the illustrated embodiment, a singlespring 160 is provided that is used for all eight jackwire contacts 140,but it will be appreciated that in other embodiments more than onespring 160 may be provided (e.g., a separate spring 160 could beprovided for each of the jackwire contacts 140).

Each of the contact carriers 150 may be mounted directly on top of arespective one of the eight fingers 164 of spring 160. Alternatively,each finger 164 of the spring may be attached to a side surface of therespective dielectric contact carriers 150. In either case, each finger164 of the spring 160 is connected to a respective one of the jackwirecontacts 140 through a respective one of the contact carriers 150. Eachfinger 164 of the spring 160 may “spring bias” its associated contactcarrier 150 and jackwire contact 140 so that when the contact carrier150 and jackwire contact 140 are pressed down a spring force is appliedthat urges the contact carrier 150 and jackwire contact 140 upwardly toreturn to their normal resting positions.

When a mating plug is received within the plug aperture 114, the plugblades deflect each respective jackwire contact 140 and its associatedcontact carrier 150 downwardly. The contact carriers 150, in turn,deflect each of the eight fingers 164 of spring 160 downwardly. As thespring 160 is resilient, the fingers 164 of the spring 160 exert anupward force on their respective contact carriers 150, thereby forcingeach of the jackwire contacts 140 upwardly to ensure that each jackwirecontact 140 engages its mating plug blade with sufficient contact forceto ensure that a reliable electrical connection is maintained betweenthe eight blades of the mating plug and the jackwire contacts 140 withwhich they respectively mate. The spring 160 may be electricallyisolated by the contact carriers 150 from the jackwire contacts 140 (andhence is not part of the signal current carrying paths).

As the resiliency of the spring 160 provides the contact force (throughthe contact carriers 150) that presses the jackwire contacts 140 againstthe respective blades of a mating plug, the jackwire contacts 140 neednot be mounted in cantilevered fashion, nor must they be resilient(although they may be). Consequently, in some embodiments, the jackwirecontacts 140 may be very short in length, which can significantly reducethe amount of coupling between adjacent jackwire contacts 140, and hencethe amount of offending crosstalk that is generated. For example, thejackwire contacts 140 may each be about 200 mils to about 230 mils inlength, in contrast with typical conventional jackwire contacts whichmay be much longer range, for example, from about 400 mils to about 800mils in length, or even more.

While not shown in the drawings, a plurality of guiding walls may beprovided in, for example, the jack housing 110 that define a pluralityof guiding slots therebetween. A portion of each of the contact carriers150 may be positioned in a respective one of these slots. Each contactcarrier 150 may move up and down within its respective slot in responseto the insertion or removal of a mating plug, but the slots act tomaintain each of the contact carriers 150, and hence the jackwirecontacts 140 mounted thereon, in their proper transverse alignmentwithin the plug aperture 114 in order to maintain the jackwire contacts140 at desired distances from each other and to ensure that the jackwirecontacts 140 are properly aligned with their mating plug blades.

As shown best in FIGS. 4, 6 and 8, the jackwire contacts 140 may bealigned in two rows in the lateral direction, with jackwire contacts140-2, 140-4, 140-6 and 140-8 mounted in a first row that is fartherforward on the flexible printed circuit board 130 than jackwire contacts140-1, 140-3, 140-5 and 140-7, which are mounted in a second row.

FIG. 8 is a schematic plan view of the flexible printed circuit board130. FIG. 8 more clearly pictures how the slots 133, 134, 135 and 137are used to form the fingers 136-1 through 136-8 and 138-1 through 138-6(note that fingers 136-2 through 136-7 are not numbered in FIG. 8 tosimplify the drawing, but are aligned in numerical order between fingers136-1 and 136-8). FIG. 8 also illustrates the metal-plated apertures139-1 through 139-8 which receive the first end 142 of jackwire contacts140-1 through 140-8, respectively, and metal-plated apertures 139-9through 139-16 that receive the second ends 146 of jackwire contacts140-1 through 140-8, respectively. The first and second ends 142, 146 ofthe jackwire contacts 140 can be permanently mounted into theirrespective metal-plated apertures 139-1 through 139-16 by anyconventional means such as, for example, welding, soldering or includingeye-of-the-needle terminations on the ends 142, 146 of each jackwirecontact 140. In this fashion, the first end 142 and the second end 146of each jackwire contact 140 may be electrically connected to conductivestructures on the flexible printed circuit board 130 in order to allowelectrical signals (and electrical power signals) to pass between theflexible printed circuit board 130 and the respective jackwire contacts140.

The flexible printed circuit board 130 may act as a signal carryingstructure that passes signals between the eight jackwire contacts 140and respective ones of eight output contacts 170 of the jack 100. Inparticular, as is shown in the schematic diagram of FIG. 8, a pluralityof conductive paths 174-1 through 174-8 are provided in or on theflexible printed circuit board 130. Each conductive path 174 connects arespective one of the metal-plated apertures 139-9 through 139-16 to acorresponding one of a plurality of metal-plated apertures 172-1 through172-8 in order to provide eight conductive paths through the flexibleprinted circuit board 130. Each conductive path 174 may be formed, forexample, as a unitary conductive trace that resides on a single layer ofthe flexible printed circuit board 130 or as two or more conductivetraces that are provided on multiple layers of the flexible printedcircuit board 130 and which are electrically connected throughmetal-filled vias or other layer transferring techniques known to thoseof skill in the art. The conductive traces 174 may be formed ofconventional conductive materials such as, for example, copper, and aredeposited on the flexible printed circuit board 130 via any depositionmethod known to those skilled in this art.

A plurality of crosstalk compensation circuits 178 such as, for example,interdigitated finger capacitors, plate capacitors, inductively couplingtraces and the like may also be provided on and/or within the flexibleprinted circuit board 130. Two exemplary capacitive crosstalkcompensation circuits 178-1, 178-2 in the form of plate capacitors (onlythe upper plate of each plate capacitor is visible) are illustrated inFIG. 8, as are two exemplary inductive crosstalk compensation circuits178-3, 178-4. Either or both the capacitive crosstalk compensationcircuits 178-1, 178-2 and/or the inductive crosstalk compensationcircuits 178-3, 178-4 may be located on portions of the flexible printedcircuit board 130 that move when a plug is inserted into the plugaperture 114 of jack 100. Each of these crosstalk compensation circuitswill be discussed in more detail below.

As shown in FIG. 7, a plurality of output terminals 170-1 through 170-8are also mounted to be in electrical contact with the flexible printedcircuit board 130. In this particular embodiment, the eight outputterminals 170 are implemented as insulation displacement contacts (IDCs)that are mounted in the metal-plated apertures 172-1 through 172-8 (seeFIG. 8) in the flexible printed circuit board 130 and extend through theboard 130 into the mounting substrate 122. As is well known to those ofskill in the art, an IDC is a type of wire connection terminal that maybe used to make mechanical and electrical connection to an insulatedwire conductor. The IDCs 170 may be of conventional construction andneed not be described in detail herein. Any other appropriate outputcontact may be used including, for example, insulation piercingcontacts.

The communications jack 100 may exhibit improved crosstalk performanceas compared to many conventional communications jacks.

As is known to those of skill in the art, modern communications jackssuch as RJ-45 jacks typically include single-stage or multi-stagecrosstalk compensation circuits that are designed to inject“compensating” crosstalk that cancels out “offending” crosstalk that isinjected between two differential pairs in a mated communications jackand plug combination due to industry-standardized configurations of theplug blades and the jackwire contacts. However, the compensatingcrosstalk typically cannot be inserted at precisely the same locationswhere the offending crosstalk is injected, and thus the compensatingcrosstalk is typically injected at some delay after the offendingcrosstalk. Unfortunately, for communications signals at higherfrequencies (e.g., at frequencies above 100 MHz and, even more so forfrequencies above 250 MHz or 500 MHz), a significant phase shift mayoccur because of the delay between the locations where the offending andcompensating crosstalk are injected, and because of this phase shift,the compensating crosstalk will not completely cancel out the offendingcrosstalk.

In an effort to address this problem caused by the delay, theaforementioned '358 patent teaches methods of using multi-stagecrosstalk compensation in communications jacks that may, theoretically,completely cancel out an offending crosstalk signal having a specificfrequency. However, since the frequency of the communications signalsthat traverse a plug jack connection are typically not known in advance,the techniques of the '358 patent may provide good, but not perfect,crosstalk cancellation at other frequencies. Moreover, because of theaforementioned phase shifts, all other things being equal, bettercrosstalk performance can typically be achieved the less offendingcrosstalk that is generated and the closer in time the compensatingcrosstalk is injected to point where the offending crosstalk isinjected.

As is known to those of skill in the art, crosstalk compensationcircuits are typically implemented in communications jacks as capacitivecrosstalk compensation circuits and as inductive crosstalk compensationcircuits. Capacitive crosstalk compensation circuits are most typicallyimplemented as plate capacitors and/or as interdigitated fingercapacitors that are implemented, for example, on a printed circuit boardof the jack or in the jackwire contacts of the jack, although othercapacitive crosstalk compensation circuits may be used. Inductivecrosstalk compensation circuits are most typically implemented asconductive paths that run side-by-side next to each other, either in thejackwire contacts or as conductive traces on a printed circuit board ofthe jack. Typically, it is desirable to implement the crosstalkcompensation scheme using both inductive crosstalk compensation circuitsand capacitive crosstalk compensation circuits so that both NEXT andFEXT can be cancelled.

In particular, it is known that in conventional modular communicationplugs and jacks capacitively coupled and inductively coupled signalcomponents add for NEXT, while they subtract for FEXT. That is:NEXT=X _(C) +X _(M)andFEXT=X _(C) −X _(M)where X_(C) is the capacitively coupled component and X_(M) is theinductively coupled component. Here, X_(C) may be viewed as thecapacitive component of the offending crosstalk and X_(M) may be viewedas the inductive component of the offending crosstalk. Thus, to cancelboth NEXT and FEXT, a communications jack should inject compensatingcrosstalk that substantially cancels both the offending NEXT and theoffending FEXT.

It is also known that NEXT cancellation may generally be improved bylimiting the amount of delay between the offending crosstalk and thecompensating crosstalk. By placing capacitive compensation at the plugjack mating point (or very close thereto in terms of delay, such as atthe non signal current-carrying end of the jackwire contacts) it may bepossible to provide very high levels of NEXT cancellation, even withrespect to high frequency signals. However, such a jack design mayexhibit poor FEXT cancellation as the compensation being provided istotally capacitive in nature. As is apparent from the equations above,in order to substantially cancel both NEXT and FEXT, some amount ofinductive compensating crosstalk is generally required if the offendingcrosstalk includes an inductive component X_(M) (which it generally doesdue to the requirements of various industry standard documents).

The communications jacks according to embodiments of the presentinvention may include a variety of features that either reduce theamount of crosstalk that is injected in the plug jack mating region, orthat facilitate the injection of compensating crosstalk at a very smalldelay. These communications jacks may also include features thatfacilitate providing good cancellation of both NEXT and FEXT, and/orwhich may provide improved return loss performance. Various suchfeatures will now be explained with respect to the embodiment of FIGS.3-9 and with respect to various modified embodiments that are discussedwith respect to the remaining figures.

Turning first to FIG. 8, as one example, capacitive crosstalkcompensation circuits such as circuits 178-1, 178-2 are provided in thefront portion 131 of the flexible printed circuit board 130. Notably,these capacitive crosstalk compensation circuits 178-1, 178-2 areattached to the first ends 142 of the jackwire contacts, and hence arenot on the signal current carrying path through the jack 100 (as asignal injected from a plug blade onto a jackwire contact 140 willtravel from the plug contact region of the jackwire contacts 140 to thesecond end 146 of the jackwire contact 140 and then across traces on theflexible printed circuit board 130 to the corresponding output terminal170). Since the crosstalk compensation circuits 178-1, 178-2 areattached to the non-signal current carrying ends of the jackwirecontacts 140, they inject that capacitive crosstalk compensation at avery small delay from the plug jack mating point. While the embodimentdepicted in FIG. 8 only shows capacitive crosstalk compensation circuits178 attached between pairs 1 and 3, it will be appreciated thatadditional crosstalk compensation circuits may be provided between otherpair combinations in further embodiments.

The jack 100 is also designed to inject inductive crosstalk compensationat a short delay from the plug jack mating point. The inductivecrosstalk compensation is provided in the jack 100 by the inductivecrosstalk compensation circuits 178-3, 178-4, each of which are formedby running two of the conductive traces on the flexible printed circuitboard close to each other so that the traces inductively couple. Inorder to inject this inductive crosstalk compensation at a relativelysmall delay, the inductive crosstalk compensation circuits may beimplemented in the flexible printed circuit board 130 very close to thesecond ends 146 of the jackwire contacts 140 (i.e., as soon as possibleto the points where the signals enter the flexible printed circuit board130 from the jackwire contacts 140). However, as is shown in FIGS. 4 and8, the longitudinal slots 137 that are provided between the fingers 138may be relatively long. As such, the shortest path distance along theflexible printed circuit board 130 between two of the metal-plated holes139 that receive the second ends 146 of two of the jackwire contacts 140may be fairly long. For example, as an extended longitudinal slot 137-1separates fingers 138-1 and 138-2, and, as a result, the longitudinalslots 137 may make it difficult to quickly provide inductive crosstalkcompensation on the flexible printed circuit board 130 since suchinductive compensation is typically implemented by running twoconductive traces side-by-side on the printed circuit board so that theyinductively couple, and the slots 137 may force a designer to implementsuch inductive crosstalk compensation at a greater distance, and hence agreater delay, from the jackwire contacts 140. As noted above, crosstalkcompensation may be more effective if it may be injected close to theplug jack mating point, and hence this delay in the injection of theinductive crosstalk compensation may make it more difficult toeffectively cancel the crosstalk.

In order to shorten this delay, the second ends 146 of two (or more) ofthe jackwire contacts 140 may be co-mounted on the same finger 138. Inparticular, as shown in FIGS. 4 and 8, the second ends 146 of jackwirecontacts 140-3 and 140-5 are both located on finger 138-3, and thesecond ends of jackwire contacts 140-4 and 140-6 are both located onfinger 138-4. This arrangement can significantly reduce the shortestpath distance the signal needs to travel before inductive coupling canbe commenced. For example, as shown in FIG. 8, the shortest pathdistance the signal needs to travel to implement inductive coupling178-4 can be considerably less than would have been the case had themetal plated apertures 139-11 and 139-13 been mounted on separatefingers similarly configured to fingers 138-1 and 138-2. The same istrue with respect to metal-plated holes 139-12 and 139-14, because theircorresponding jackwire contacts 140-4 and 140-6 are also co-located onthe same finger 138-4.

As shown on FIG. 8, the conductive traces 174-3 and 174-5 that areconnected to the metal-plated apertures 139-11 and 139-13 include aninductive coupling section 178-4 that provides inductive crosstalkcompensation between pairs 1 and 3. Likewise, the conductive traces174-4 and 174-6 that are connected to the metal-plated apertures 139-12and 139-14 include an inductive coupling section 178-3 that alsoprovides inductive crosstalk compensation between pairs 1 and 3. Theinductive coupling sections 178-3, 178-4 are each located a very shortdistance, and hence a short delay, from the jackwire contacts 140, andthus may provide more effective crosstalk compensation.

The design of the jackwire contacts 140 may also improve the crosstalkperformance of the jack 100. Most conventional RJ-45 communicationsjacks implement the plug contacts using spring jackwires that areelongated contact wires that are formed of beryllium-copper orphosphor-bronze. These contact wires may be formed to be sufficientlyresilient such that the plug contact will meet industry standardizedspecifications with respect to the contact force that each jackwirecontact applies to a mating plug blade and/or to ensure that thejackwire contacts do not become permanently deformed with use.Typically, relatively long jackwire contacts must be used in order toensure that the jackwire contacts provide the requisite contact force.In contrast, the jackwire contacts 140 that may be included incommunications jacks according to embodiments of the present inventionmay be significantly shorter, and thus the signal current carrying paththrough each of the jackwire contacts 140 may be very short in length.In particular, the signal current carrying path through each jackwirecontact 140 extends from the middle region 144 of the jackwire contact140 (i.e., the part of the jackwire contact that engages a mating plugblade) to the second end 146 of the jackwire contact 140. In someembodiments, the length of each jackwire contact 140 may be betweenabout 200 mils and about 230 mils, which is far less than the length ofmost conventional spring jackwire contacts. As a result, the coupling,and hence the crosstalk, between adjacent jackwire contacts 140 may besignificantly reduced.

Additionally, the jackwire contacts 140 may be aligned in two staggeredrows in the transverse direction. This stagger may readily be seen inthe perspective view of communications insert 120 provided in FIG. 4 andin the plan view of the flexible printed circuit board 130 of FIG. 8(which shows the mounting vias for the jackwire contacts 140). As shownin FIG. 6, the jackwire contacts 140 are designed so that each contact140 engages the bottom, longitudinal surface of a mating plug blade.Pursuant to various industry standards, an RJ-45 plug must include eightslots that extend from a lower portion of the front face of the plughousing and along the forward portion of the bottom face of the plughousing. Likewise, each blade of the RJ-45 plug must have a front regionthat is exposed through the portion of the slot that is in the frontface of the plug housing, a bottom region that is exposed through theportion of the slot that is in the bottom face of the plug housing, anda curved transition region that connects the front and bottom regions ofthe plug blade.

Conventionally, jackwire contacts on an RJ-45 jack are generallydesigned to engage the curved transition region of their respectiveblades of an RJ-45 plug when the plug is fully received within the plugaperture of the jack. As a result, even if the jackwire contacts have adegree of stagger when in their resting position, when the jackwirecontacts are engaged by the blades of a mating plug that is receivedwithin the plug aperture of the jack, the jackwire contacts tend tobecome aligned in a row as they each press against the curved transitionregion of their mating plug blades. By designing the jackwire contacts140 to engage the bottom, longitudinal surface of their mating plugblades, the stagger in the jackwire contacts 140 that is present whenthe jackwire contacts 140 are in their normal resting positions (seeFIGS. 4 and 8) may be maintained even when a plug is received within theplug aperture 114 of the jack 100, as is shown in FIG. 6.

By aligning the jackwire contacts 140 so that they will stay in twostaggered rows even when a plug is received within the plug aperture 114of jack 100, it is possible to further reduce the amount of offendingcrosstalk that is generated between the differential pairs. By way ofexample, in a conventional RJ-45 jack illustrated in FIG. 2, in the plugjack mating region jackwire contact 2 (which is part of pair 2) willgenerally couple a greater amount of signal energy onto jackwire contact3 (which is part of pair 3) than will jackwire contact 1 (which is theother jackwire contact of pair 2), as jackwire contact 2 is directlyadjacent to jackwire contact 3, while jackwire contact 1 is positionedfarther away from jackwire contact 3. Consequently, this unequalcoupling by the conductors of pair 2 onto pair 3 results in offendingcrosstalk from pair 2 onto pair 3 (and vice versa). Referring now toFIGS. 4 and 6, it can be seen that in the jack 100 according toembodiments of the present invention jackwire contact 140-2 is staggeredwith respect to jackwire contacts 140-1 and 140-3 (since jackwirecontact 140-2 is positioned forwardly in a first row while jackwirecontacts 140-1 and 140-3 are positioned in rearwardly in a second row),the amount of coupling between jackwire contact 140-2 and 140-3 can bereduced, thereby reducing the amount of unequal coupling from theconductors of pair 2 onto jackwire contact 140-3. Similar beneficialreductions in the amount of offending crosstalk may be achieved on eachadjacent pair combination. Thus, the staggering of the input contacts140 into first and second rows may further reduce the amount ofoffending crosstalk generated in the jack 100.

In some embodiments, the jackwire contacts 140 may be staggeredsufficiently such that the jackwire contacts of at least one pair may be“neutral” with respect to at least one other pair. Herein, two pairs ofjackwire contacts are considered to be “neutral” if they do not generateany crosstalk at any point along the lengths of the jackwire contacts140. Note that if two pairs of jackwire contacts 140 are “neutral” thenany subsections of these jackwire contacts 140 will also be neutral withrespect to each other, as the neutrality (i.e., the absence of anycrosstalk) must be present along the entire lengths of the jackwirecontacts 140 for the two pairs of jackwire contacts 140 to be consideredneutral. In the embodiment depicted in FIGS. 3-9, the jackwire contacts140 for pair 1 (140-4, 140-5) and pair 3 (140-3, 140-6) are designed tobe neutral. Neutrality may also be achieved between pairs 1 and 2 andbetween pairs 1 and 4. Neutrality may be more difficult to achievebetween pair 3 and either pair 2 or pair 4, given the splitconfiguration of the jackwire contacts 140-3, 140-6 of pair 3.

Neutrality between differential pairs of jackwire contacts may bedesirable because, generally speaking, the less offending crosstalk thatis generated the better the performance of the jack, given thedifficulty of perfectly cancelling offending crosstalk. If the jackwirecontacts are neutral, then no additional offending crosstalk isgenerated in the leadframe, and the jack may only need to compensate forthe offending crosstalk that is generated in the plug as specified inthe relevant industry standards documents. This may result in improvedcrosstalk performance. While the jack 100 provides for neutralitybetween pairs 1 and 3 by aligning the plug contact regions of thejackwire contacts in two transverse rows, it will be appreciated that inother embodiments the plug contact regions of the contacts may bealigned in, for example, more than two rows. It will also be appreciatedthat while neutrality provides certain benefits, jacks may be providedthat do not achieve neutrality in the leadframe between some pairs (oreven between any pairs). However, by using a stagger or other techniquesto reduce the amount of offending crosstalk that is generated in theleadframe improved crosstalk performance may be achieved.

In some embodiments, the staggered jackwire contacts may be designed tonot only be neutral, but to in fact generate compensating crosstalkbetween one or more of the pairs. This may be accomplished byexaggerating the stagger, in a variety of ways, in order to reduce theoffending crosstalk between adjacent jackwire contacts to a level thatis lower than the compensating crosstalk generated between the one-overjackwire contacts. In some embodiments, horizontal and/or verticalstaggers may be provided between adjacent jackwire contacts that aresufficient that the jackwire contacts couple more heavily with a“one-over” jackwire contact than they do with an adjacent jackwirecontact. Thus, in these embodiments, compensating crosstalk may begenerated at a small delay from the plug contact regions of the jackwirecontacts by generating at least some of the compensating crosstalk inthe leadframe. Typically, capacitive compensating crosstalk may readilybe injected at a small delay by connecting capacitors to non-signalcurrent carrying ends of the jackwire contacts. However, inductivecompensating crosstalk is often injected only after signals are routedonto a printed circuit board of the jack, and hence may be at a largerdelay. The staggered jackwire contacts according to embodiments of thepresent invention may be designed to inject inductive compensatingcrosstalk within the leadframe, and hence may inject such compensatingcrosstalk at shorter delays, which may improve the crosstalkcancellation performance of the jack.

As shown best in FIG. 6, in some embodiments, the staggered jackwirecontacts 140 may be designed to engage the bottom (longitudinal) surfaceof the respective blades of a mating plug as opposed to the curvedtransition sections of the plug blades that connect the front surfaceand bottom surface of each plug blade. As a result, the stagger in thejackwire contacts 140 may be maintained even when a plug is fullyreceived within the plug aperture of the jack. In some embodiments, fourjackwire contacts 140 may generally be aligned in a first transverse rowand the other four jackwire contacts are aligned in a second transverserow. In some embodiments, the first transverse row may be at least about20 mils forward of the second transverse row. In other embodiments, thefirst transverse row may be at least about 30 mils forward of the secondtransverse row. In some specific embodiments, the first transverse rowmay be between 20 mils and 40 mils forward of the second transverse row.

FIG. 6A is a schematic side cross-sectional view of the front portion ofa communications insert 120′ that is a slightly modified version of thecommunications insert 120 of FIG. 4. The cross-sectional view of FIG. 6Ais taken along the longitudinal length of one of the jackwire contactsof the communications insert 120′.

As shown on FIG. 6A, the communications insert 120′ may be almostidentical to the communications insert 120 that is described above,except that the rear row of jackwire contacts 140′ are positioned evenfurther rearwardly in the plug. In particular, while the two rows ofjackwire contacts 140 of the communications insert 120 were spaced apartin the longitudinal direction by 30 mils, in the embodiment of FIG. 6Athis separation has been increased to about 50 mils. This has at leasttwo effects. First, the increased separation along the longitudinal(horizontal in FIG. 6A) dimension decreases the amount of offendingcrosstalk that is generated between adjacent jackwire contacts in theleadframe. Second, the rear row of jackwire contacts 140′ now engage theplug blades along the curved transition region thereof, and hence maynot be pushed downwardly as far in the vertical direction as the frontrow of jackwire contacts 140′. This may provide for a small verticalstagger which is provided in addition to the above-discussed horizontalstagger. This may also further decrease the amount of offendingcrosstalk that is injected in the leadframe.

As discussed above, in some embodiments of the present invention,capacitive crosstalk compensation may be provided in the jack 100 usingcrosstalk compensation circuits 178-1, 178-2 that are attached to thenon-signal current carrying ends of various of the jackwire contacts, asshown in FIG. 8. These crosstalk compensation capacitors 178-1, 178-2may inject compensating crosstalk at a very short delay from theplug-jack mating point. However, it will be appreciated that othermechanisms may be used to inject capacitive compensating crosstalkbetween the pairs in the jack at very short delays from the plug jackmating point.

In particular, in some embodiments, a small printed circuit board may bemounted directly onto the middle portions of some of the jackwirecontacts 140. By way of example, FIG. 10 is a schematic perspective viewof a portion of a communications insert 220 for a communications jackthat is very similar to the communications insert 120, but whichreplaces the above-discussed crosstalk compensation circuits 178-1,178-2 with a printed circuit board 270 that is mounted on the jackwirecontacts 140. FIG. 11 is a schematic plan view illustrating both the topand bottom layers of the printed circuit board 270.

As shown in FIGS. 10 and 11, the printed circuit board 270 may bemounted (e.g., by soldering or welding) to the underside of jackwirecontacts 140-3 through 140-6. The printed circuit board 270 maycomprise, for example, a flexible printed circuit board 270. Theflexible nature of such a flexible printed circuit board 270 may allowthe jackwire contacts 140-3 through 140-6 to move with some degree ofindependence, as may be required to ensure that each plug blade of amating plug engages the jackwire contacts 140-3 through 140-6 withsufficient contact force.

As shown best in FIG. 11, the flexible printed circuit board 270 mayinclude a plurality of solder pads 272-1 through 272-4. These solderpads 272 may be aligned in one or more transverse rows, and may belongitudinally aligned with the respective jackwire contacts 140-3through 140-6. Each jackwire contact 140-3 through 140-6 may be solderedto a respective one of the solder pads 272-1 through 272-4 in order tomount the flexible printed circuit board 270 on the underside of thejackwire contacts 140-3 through 140-6 and to electrically connect eachjackwire contact 140-3 through 140-6 to crosstalk compensation circuitsthat are provided on the flexible printed circuit board 270. In thedepicted embodiment, the solder pads 272 are aligned in two transverserows, with solder pads 272-1 and 272-3 being farther rearward thansolder pads 272-2 and 272-4. This configuration allows each solder pad272 to be positioned on the bottom side of its respective jackwirecontact 140-3 through 140-6 so that it is directly opposite the plugcontact region of the respective jackwire contacts 140-3 through 140-6.This may facilitate reducing or minimizing the delay between thecrosstalk compensation circuits provided on the flexible printed circuitboard 270 and the plug contact regions of the jackwire contacts 140-3through 140-6. In such an embodiment, the compensating crosstalk signalmay be injected onto the signal current-carrying path at a very shortdistance from the plug contact region on each jackwire contact 140,which distance may be as small as the thickness of the jackwire contact140.

Still referring to FIG. 11, it can be seen that in the depictedembodiment, two crosstalk compensation circuits 278-1, 278-2 areprovided on the flexible printed circuit board 270. The crosstalkcompensation circuit 278-1 comprises a plate capacitor that is formed bya pair of parallel plates that are disposed on opposite sides of theflexible printed circuit board 270, where the plates are separated bythe dielectric layer of the flexible printed circuit board 270. The topplate is connected to solder pad 272-1 by a conductive trace formed onthe top side of the flexible printed circuit board 270 and the bottomplate is connected to solder pad 272-3 by a conductive trace formed onthe bottom side of the flexible printed circuit board 270. The crosstalkcompensation circuit 278-1 injects first stage capacitive compensatingcrosstalk between pairs 1 and 3 that has a polarity opposite thepolarity of the offending crosstalk that is injected between pairs 1 and3 in an industry standards compliant RJ-45 plug.

The crosstalk compensation circuit 278-2 similarly comprises a platecapacitor that is formed by a pair of parallel plates that are disposedon opposite sides of the flexible printed circuit board 270. The topplate of this capacitor is connected to solder pad 272-4 by a conductivetrace formed on the top side of the flexible printed circuit board 270and the bottom plate of the capacitor is connected to solder pad 272-2by a conductive trace formed on the bottom side of the flexible printedcircuit board 270. The crosstalk compensation circuit 278-2 also injectsfirst stage capacitive compensating crosstalk between pairs 1 and 3 thathas a polarity opposite the polarity of the offending crosstalk that isinjected between pairs 1 and 3 in an industry standards compliant RJ-45plug. As noted above, the crosstalk compensation circuits 278-1, 278-2may be used to replace (or augment) the crosstalk compensation circuits178-1, 178-2 that are provided in the jack 100 of FIGS. 3-9.

The flexible printed circuit board 270 includes a plurality of slits274-1 through 274-3. These slits 274 define four areas on the flexibleprinted circuit board (namely an area that is disposed under eachrespective jackwire contact 140-3 through 140-6), and allow each area tobend or flex with some degree of independence from the other areas. Thisallows some of the jackwire contacts 140 to be depressed differentdistances from other of the jackwire contacts 140 without placing unduestress or force on the soldered connections between the flexible printedcircuit board 270 and the jackwire contacts 140-3 through 140-6.

While the flexible printed circuit board 270 depicted in FIGS. 10 and 11only shows capacitive crosstalk compensation circuits 278 attachedbetween pairs 1 and 3, it will be appreciated that additional crosstalkcompensation circuits may be provided between other pair combinations infurther embodiments. For example, capacitive crosstalk compensation maybe provided in the form of additional capacitors between pairs 2 and 3(e.g., a capacitor on the flexible printed circuit board 270 that isconnected to jackwire contacts 140-1 and 140-3) and between pairs 3 and4 (e.g., a capacitor on the flexible printed circuit board 270 that isconnected to jackwire contacts 140-6 and 140-8).

FIG. 12 is a schematic perspective view of a portion of a communicationsinsert 320 for a communications jack according to still furtherembodiments of the present invention. The communications insert 320 isvery similar to the communications insert 220 that is discussed abovewith respect to FIGS. 10 and 11. However, the communications insert 320replaces the flexible printed circuit board 270 of communications insert220 with a pair of flexible printed circuit boards 370-1, 370-2 that aremounted (e.g., by soldering or welding) to the underside of jackwirecontacts 140-3 through 140-6.

The flexible printed circuit boards 370-1 and 370-2 may each contain acrosstalk compensation circuit. For example, the flexible printedcircuit board 370-1 may be mounted (e.g., by soldering or welding) tothe underside of jackwire contacts 140-3 and 140-5 and may include thecrosstalk compensation capacitor 278-1 (see FIG. 11). The flexibleprinted circuit board 370-2 may be mounted (e.g., by soldering orwelding) to the underside of jackwire contacts 140-4 and 140-6 and mayinclude the crosstalk compensation capacitor 278-2 (see FIG. 11). Eachflexible printed circuit board 370-1, 370-2 may include a slit (notshown) that are similar to the slits 274 of flexible printed circuitboard 270. By replacing the single flexible printed circuit board 270 ofFIGS. 10 and 11 with the two flexible printed circuit boards 370-1,370-2 that are depicted in FIG. 12 it may be possible to reduceunintended coupling between the crosstalk compensation circuits and itmay also be possible to allow for more independence of movement betweenthe jackwire contacts 140-3 through 140-6 (since each jackwire contact140 is only connected at most to one other jackwire contact 140 via thejackwire contact mounted printed circuit boards 370 and because theslits in the flexible printed circuit boards 370-1, 370-2 may bepositioned farther away from the solder pads.

FIG. 13 is a schematic perspective view of a flexible printed circuitboard 470-1 that may be used instead of the flexible printed circuitboard 370-1 that is depicted in FIG. 12. The flexible printed circuitboard 470-1 may be very similar to the flexible printed circuit board370-1 except that the flexible printed circuit board 470-1 includes abend or crease 476 (herein bends or creases are generically referred toas a “fold”). The flexible printed circuit board 470-1 may, for example,be soldered (via solder pads 472-1, 472-2) to jackwire contacts 140-3and 140-5, respectively. The fold 476 allows the jackwire contacts 140-3and 140-5 to freely move different amounts in response to the insertionof a communications plug into the plug aperture 114 of the jack 100, asthe fold 476 may crease more or less heavily, as necessary, in responseto such non-uniform movement of the jackwire contacts 140-3, 140-5. Theprovision of one or more folds 476 may eliminate any need for the slits274 that are provided on flexible printed circuit board 270, as thefold(s) 476 and the slits 274 may serve the same purpose. However, insome embodiments, both folds and slits may be provided on the samejackwire contact 140 mounted flexible printed circuit board to furtherincrease the ability of the jackwire contacts 140 that the flexibleprinted circuit board is mounted on to move independently.

Thus, pursuant to embodiments of the present invention, communicationsjacks are provided that have a housing, a printed circuit board that isat least partially mounted within the housing, and a plurality ofjackwire contacts. Each jackwire contact has a base portion that ismounted in the printed circuit board and a plug blade contact surface. Aflexible printed circuit board is mounted on at least two of thejackwire contacts and includes at least one crosstalk compensationcircuit. The plug blade contact surfaces of some of the jackwirecontacts may be aligned in a first transverse row, and others of thejackwire contacts may be aligned in a second transverse row that isoffset from the first transverse row. In some embodiments, the printedcircuit board that receives the base ends of the jackwire contacts maybe a flexible printed circuit board. A mounting substrate may beprovided underneath the flexible printed circuit board so that thejackwire contacts are mounted through the flexible printed circuit boardand into the mounting substrate (and hence the jackwire contacts aremounted in both the flexible printed circuit board and in the mountingsubstrate). The jack may be an RJ-45 jack, and the flexible printedcircuit board may include crosstalk compensation circuits that injectcompensating crosstalk between pairs 1 and 3.

As shown in FIG. 11A, in further embodiments of the present invention, ajackwire contact mounted flexible printed circuit board 270′ may beprovided that includes both capacitive and inductive compensatingcrosstalk circuits. The flexible printed circuit board 270′ is similarto the flexible printed circuit board 270 shown in FIGS. 10 and 11, andmay be used in place of the flexible printed circuit board 270. Theflexible printed circuit board 270′ includes six solder pads 272,namely, the four solder pads 272-1 through 272-4 that are discussedabove as well as two additional solder pads 272-5 and 272-6. Solder pads272-5 and 272-6 are longitudinally aligned with solder pads 272-1 and272-3, respectively. Jackwire contact 140-3 is mechanically andelectrically connected to both solder pads 272-1 and 272-5, jackwirecontact 140-4 is mechanically and electrically connected to solder pad272-3, jackwire contact 140-5 is mechanically and electrically connectedto both solder pads 272-3 and 272-7, and jackwire contact 140-6 ismechanically and electrically connected to solder pad 272-4.

As shown in FIG. 11A, the flexible printed circuit board includes thecapacitive crosstalk compensation circuits 278-1, 278-2 that arediscussed above with respect to FIG. 11. In addition, the flexibleprinted circuit board 270′ includes an inductive crosstalk compensationcircuit 279. The inductive crosstalk compensation circuit 279 is formedby running a first trace 280 from solder pad 272-1 on the top side offlexible printed circuit board 270′ to generally extend between pads272-3 and 272-6. The first trace 280 then runs transversely to attach tosolder pad 272-5. A second trace 282 is run on the bottom side offlexible printed circuit board 270′ from solder pad 272-3 to solder pad272-6, and hence runs directly or almost directly below a portion of thefirst trace 280. A portion of the signal current on jackwire contact140-3 will be routed onto the first trace 280 (i.e., a signal injectedonto contact 140-3 will be split, with a first portion of the signaltraversing the jackwire contact 140-3 and a second portion of the signalpassing through solder pad 272-1, trace 280 and solder pad 272-5 andthen back onto the jackwire contact 140-3). Likewise, a portion of thesignal current on jackwire contact 140-5 will be routed onto the secondtrace 282 in a similar fashion. The signals traversing the first andsecond traces 280, 282 will inductively couple to provide inductivecompensating crosstalk, thereby forming the inductive crosstalkcompensation circuit 279.

Pursuant to further embodiments of the present invention, communicationsjacks are provided that can very effectively cancel both NEXT and FEXT.In particular, U.S. Pat. No. 6,464,541 (“the '541 patent”), issued Oct.15, 2002, sets forth techniques where first stage compensating crosstalkthat is injected at a small delay may be used to cancel NEXT, and asecond stage of compensating crosstalk which includes equal but oppositeamounts of inductive and capacitive crosstalk may be used to adjust therelative amounts of inductive and capacitive crosstalk compensation inorder to improve the FEXT cancellation of the jack. Pursuant toembodiments of the present invention, the concepts of the '541 patentmay be modified and implemented on a flexible printed circuit board in amanner that can provide very effective crosstalk cancellation. FIG. 14is a vector diagram illustrating such a crosstalk compensation schemefor cancelling both NEXT and FEXT according to embodiments of thepresent invention that may be used, for example, in a communicationsjack.

As shown in FIG. 14, two stages 501, 502 of crosstalk compensation areprovided within an RJ-45 communications jack 500 that may be used tocancel offending crosstalk 503. As discussed above, a mating connectorin the form of an industry standards compliant RJ-45 communication plugwill introduce offending crosstalk between various of the differentialpairs. The vectors 510 and 511 represent the offending crosstalk that isintroduced between pairs 1 and 3 in the mating communications plug. Thisoffending crosstalk includes inductive offending crosstalk andcapacitive offending crosstalk. The offending crosstalk between pairs 1and 3 is generated in the plug by coupling between plug blades 3 and 4and between plug blades 5 and 6. In FIG. 14, vector 510 represents theinductive component Xmo of the offending crosstalk generated in the plugbetween pairs 1 and 3 in the plug 505 and the vector 511 represents thecapacitive component Xco of the offending crosstalk generated in theplug between pairs 1 and 3. Typically, the capacitive component Xcofollows the inductive component Xmo after only a relatively short delay,although the relative positions of vectors 510 and 511 may varydepending on the design of the plug.

As shown in FIG. 14, capacitive crosstalk compensation Xc1 (vector 512)that has a magnitude that is the same or approximately equal to Xco+Xmoand which has opposite polarity, is introduced in a first stage 501(Stage 1) of crosstalk compensation. The capacitive crosstalkcompensation Xc1 may be injected between pairs 1 and 3 at a point thatis very close in time to the point in time where the offending crosstalkis injected. For example, as shown in FIG. 14, the capacitive crosstalkcompensation Xc1 may be injected at approximately the same point in timeas the offending capacitive crosstalk Xc0. Since the capacitivecrosstalk compensation Xc1 is injected by the first stage 501 at aminimal delay and has a magnitude equal to the sum of the magnitudes ofthe inductive and capacitive offending crosstalk (with oppositepolarity), a high degree of NEXT cancellation may be achieved.

To cancel FEXT without degrading NEXT, the second stage 502 of crosstalkcompensation is provided, as shown in FIG. 14. The second stage 502includes an inductive crosstalk compensation component Xm2 and acapacitive crosstalk compensation component Xc2 that is equal inmagnitude and of opposite polarity to the inductive component Xm2. Thus,the capacitive crosstalk component Xc2 has the same polarity as theoffending crosstalk that is injected in stage 0. Both Xm2 and Xc2 mayhave the same magnitude as the inductive component of the offendingcrosstalk Xm0. The capacitive coupling component Xc2 and the inductivecompensation component Xm2 may be injected at the same time to besubstantially self-cancelling.

As can be seen in FIG. 14 that the second stage 502 produces therequired capacitive-for-capacitive and inductive-for-inductivecompensations needed to cancel FEXT. Although the first and the secondstages 501, 502 are delayed from one another, FEXT cancellation issubstantially delay insensitive and may not be significantly affected.Also, the second stage 502 is self-canceling, and can be convenientlypositioned in time or distance with respect to the first stage 501,without degrading NEXT performance.

Accordingly, to compensate for both NEXT and FEXT simultaneously, thecapacitive component Xco of the offending crosstalk is effectivelycanceled by capacitively coupled crosstalk of equal magnitude andopposite polarity, and the offending inductive component Xmo iseffectively canceled by inductively induced crosstalk of equal magnitudeand opposite polarity.

In further embodiments, the crosstalk compensation scheme of FIG. 14could be modified so that the Xm2 component of second stage 502 is movedtoward the left slightly (i.e., closer to the plug-jack mating point) toprovide even more effective cancellation of NEXT. In this embodiment,the residual crosstalk that is provided because of the imperfectcrosstalk cancellation in the second stage 502 may be used to cancelresidual crosstalk that exists because the first stage 501 fails tocompletely cancel the offending crosstalk generated in the plug (i.e.,vectors 510 and 511). In one example implementation of this embodiment,an RJ-45 jack (T-568B) may include a first crosstalk compensation stagethat is configured to cancel crosstalk introduced between the first andthird differential pairs of conductive paths in a mating RJ-45 plug andany crosstalk injected between the first and third differential pairs ofconductive paths at the plug jack interface. The jack may furtherinclude a second crosstalk compensation stage that comprises at least aninductive coupling section between either the third conductive path andthe fourth conductive path or between the fifth conductive path and thesixth conductive path. The jack may also have a third crosstalkcompensation stage that comprises at least a first capacitor that iscoupled between either the third conductive path and the fourthconductive path or between the fifth conductive path and the sixthconductive path. The first capacitor may be a distributed capacitor thatinjects capacitance at multiple locations between the first and thirddifferential pairs of conductive paths. The second and thirdcompensating stages may have substantially equal but oppositemagnitudes. Moreover, a weighted mid-point of the second crosstalkcompensation stage may be positioned between a weighted mid-point of thefirst crosstalk compensation stage and a weighted mid-point of the thirdcrosstalk compensation stage. Herein, the “weighted mid-point” of acrosstalk compensation stage refers to the point along each conductivepath where the same amount of crosstalk is injected by the crosstalkcompensation stage on either side of the point. Typically, the weightedmid-point of the second compensation stage will be closer to theweighted mid-point of the third compensation stage that to the weightedmid-point of the first compensation stage.

The aforementioned '541 patent teaches using a leadframe design that hasa first portion where additional offending crosstalk is injected (theportion where the jackwire contacts are all aligned in a row) and asecond portion which is made to be neutral. The first stage crosstalkcompensation is introduced using capacitors that are disposed on anauxiliary printed circuit board that electrically connects to the distalends of the jackwire contacts. The inductive component of the secondstage crosstalk compensation is implemented as two pairs of inductivelycoupling traces on the main printed circuit board (which couple betweencontacts 3 and 5 and between contacts 4 and 6) and the capacitivecomponent of the second stage crosstalk compensation is implemented astwo interdigitated capacitors on the main printed circuit board (whichcouple between contacts 3 and 4 and between contacts 5 and 6). Theseinterdigitated capacitors are attached at the midpoints of therespective pairs of coupling traces that inject the second stageinductive crosstalk compensation.

The design disclosed in the '541 patent may provide good crosstalkcompensation, but may not be ideal for certain high frequencyapplications. For example, as noted above, the leadframe includes asection where significant offending crosstalk may be generated. Thus, itmay be necessary to not only cancel the offending crosstalk that isgenerated in the plug, but also the additional offending crosstalk thatis generated in the leadframe, Additionally, in the second stage, thecapacitive crosstalk is injected using lumped elements (interdigitatedfinger capacitors). While these interdigitated finger capacitors arepositioned at the mid-point of the inductive crosstalk compensation, thecapacitive crosstalk compensation will all be injected at a singlepoint, while the inductive crosstalk will be injected over time. As aresult, the inductive and capacitive crosstalk cancellation in thesecond stage will not be perfect over an extended frequency range.

Pursuant to embodiments of the present invention, superior crosstalkcancellation may be achieved by modifying the implementation disclosedin the '541 patent. As discussed above with respect to the jack 100 ofFIGS. 3-9, the jackwire contacts 140 may be staggered with respect toeach other so that the jackwire contacts may be neutral, at least forsome of the pair combinations (specifically including the pair 1 andpair 3 combination that has the most crosstalk). Thus, the jacksaccording to embodiments of the present invention may only need tocancel the offending crosstalk that is injected in the plug, at leastfor some pair combinations.

Additionally, the second stage compensation is injected on the flexibleprinted circuit board. As discussed above, the dielectric layer in aflexible printed circuit board may be much, much thinner than thedielectric layer on a conventional printed circuit board (e.g., twentytimes as thin) As such, if inductively coupling traces are arranged onopposed sides of the dielectric layer of a flexible printed circuitboard (in contrast to the side-by-side coupling traces on a conventionalprinted circuit board in the embodiment of the '541 patent), much higherlevels of inductive crosstalk may be generated per unit length ofinductively coupling traces. As such, even if lumped element capacitorsare used in the second stage, the inductive and capacitive components ofthe second stage compensation may be more closely matched in time, andhence will be closer to being self-cancelling.

Furthermore, pursuant to some embodiments of the present invention, thesecond stage compensation may be implemented as coupling traces onopposite sides of a flexible printed circuit board that couple bothinductively and capacitively. In order to have the capacitive andinductive crosstalk have opposite polarities (as is necessary for aself-cancelling second stage), the tip conductor or one pair (e.g.,conductor 3) is designed to couple with a ring conductor of the otherpair (e.g., conductor 4). This will introduce capacitive crosstalkhaving the same polarity as the offending crosstalk. However, in orderto generate inductive crosstalk having the opposite polarity, thedirection of one of the coupling traces is reversed so that, in thecoupling portion, its furthest end from the plug-jack interface, interms of current travel, couples most with the nearest end from theplug-jack interface, in terms of current travel, of the other trace andvice versa. Thus, in the above fashion, a pair of traces may be used tosimultaneously inject both capacitive crosstalk and inductive crosstalkthat have opposite polarities.

Moreover, the coupling may be designed so that the amount of capacitivecoupling per unit length is substantially equal to the amount ofinductive coupling per unit length. In particular, by controlling and/oradjusting the widths of the coupling traces and/or the degree of overlapof the inductively coupling traces, the amount of inductive andcapacitive coupling per unit length may be equalized. When this is done,the inductive and capacitive coupling may be arranged to be trulyself-cancelling since the amount of inductive and capacitive couplingwill be equal at all points along the second stage. This maysignificantly improve the crosstalk performance of the connector.

FIG. 15 is a schematic plan view of a flexible printed circuit board 530of a communications insert that implements the compensation scheme ofFIG. 14. The flexible printed circuit board 530 may be very similar tothe flexible printed circuit board 130 discussed above with respect toFIG. 8, and may be used in the communications jack 100 in place of theflexible printed circuit board 130.

The printed circuit board 530 may use the contacts 140 that areillustrated in FIG. 4. Thus, the leadframe may, for example, be neutralbetween pairs 1 and 3, thus reducing and/or minimizing the amount ofcrosstalk that must be compensated for in the jack 100. Additionally,the printed circuit board 530 includes the crosstalk compensationcircuits 178-1, 178-2. These may be used to generate the first stagecrosstalk compensation 501 discussed above with respect to FIG. 14. Thecrosstalk compensation circuits 178-1, 178-2 may be sized to cancel theinductive and capacitive crosstalk that is generated in a mating plug.

In addition, the printed circuit board 530 includes a second stagecrosstalk compensation circuit 578. As shown in FIG. 15, the secondcrosstalk compensation circuit is implemented by a pair of couplingtrace segments 579-1 and 579-2. The trace segment 579-1 is part ofconductive path 174-4 (i.e., the conductive path that connects the baseof jackwire contact 140-4 to the IDC 170-4). In particular, tracesegment 579-1 is the portion of conductive path 174-4 that it is routedtoward the front of the flexible printed circuit board 530 (i.e., theportion between the 180 degree turns in conductive path 174-4). As shownin FIG. 15, the trace segment 579-1 may be widened as compared to thetraces used to form the remainder of conductive path 174-4. The tracesegment 579-2 is part of conductive path 174-3 (i.e., the conductivepath that connects the base of jackwire contact 140-3 to the IDC 170-3).Trace segment 579-2 may also be widened as compared to the traces usedto form the remainder of conductive path 174-3. Trace segment 579-2extends on the top side of the flexible printed circuit board 530 andmay be directly opposite the trace 579-1 (which is on the bottom side ofthe flexible printed circuit board 530) so that the trace segments 579-1and 579-2 are, for example, partially or completely overlapping whenviewed from above.

As the trace segments 579-1 and 579-2 are routed on opposite sides ofthe flexible printed circuit board in an overlapping manner, the tracesegments 579-1 and 579-2 will capacitively couple. The trace segments579-1 and 579-2 will also inductively couple. Some or all of tracesegments 579-1, 579-2 may comprise widened traces, which may increasethe degree of capacitive coupling. Since the trace segments 579-1 and579-2 are routed in opposite directions (i.e., trace segment 579-1 isrouted such that its furthest end from the plug jack interface, in termsof current travel, couples most with the nearest end from the plug jackinterface, in terms of current travel, of the trace segment 579-2 andvice versa), the polarity of the inductive coupling will be opposite thepolarity of the capacitive coupling, as is required for the second stageof the crosstalk compensation scheme illustrated in FIG. 14. Moreover,the widths of the overlapping portion of trace segments 579-1, 579-2and/or the degree of overlap may be selected so that the capacitivecoupling between the traces 579-1, 579-2 may be equal in magnitude(while opposite in polarity) to the inductive coupling between thetraces 579-1, 579-2. This, FIG. 15 illustrates an embodiment that can,theoretically, perfectly implement the transparent second stage 502 ofthe crosstalk compensation scheme of FIG. 14.

Note that in the embodiment of FIG. 15, the inductive coupling sections178-3 and 178-4 of the embodiment of FIGS. 3-9 are omitted. Theseinductive coupling sections 178-3 and 178-4 may be unnecessary becausethe inductive coupling traces 579-1, 579-2 may be used to compensate forthe inductive crosstalk in a mating plug.

As can also be seen in FIG. 15, the printed circuit board 530 includes atotal of eight rear fingers 538-1 through 538-8 as opposed to the sixrear fingers 138-1 through 138-6 that are provided in the embodiment ofFIGS. 3-9. As discussed above, the embodiment of FIG. 15 includes asecond stage in which the tip conductive trace of one pair and a ringconductive trace of another pair are configured to impart inductivecompensation in the amount needed to ensure perfect FEXT cancellation inthe mated plug jack combination. Thus, it is unnecessary andcounter-productive to add more inductive compensation and hence thetransversely disposed fingers of the embodiment of FIGS. 3-9 may beomitted, and instead only longitudinal fingers may be used, with eachjackwire contact 140 having its own respective rear finger 138.

Thus, pursuant to embodiments of the present invention, communicationsjacks are provided that include a plurality of input contacts, aplurality of output contacts and a plurality of conductive paths thateach electrically connect a respective one of the input contacts to arespective one of the output contacts, the conductive paths beingarranged as a plurality of differential pairs of conductive paths. Afirst crosstalk compensation stage is provided between first and secondof the differential pairs of conductive paths, the first crosstalkcompensation stage configured to inject crosstalk having a firstpolarity between the first and second of the differential pairs ofconductive paths. The first crosstalk compensation stage may comprisecapacitive compensating crosstalk. Additionally, a second crosstalkcompensation stage is provided between the first and second of thedifferential pairs of conductive paths, the second crosstalkcompensation stage including an inductive sub-stage that is configuredto inject inductive crosstalk having the first polarity between thefirst and second of the differential pairs of conductive paths and acapacitive sub-stage that is configured to inject capacitive crosstalkhaving a second polarity between the first and second of thedifferential pairs of conductive paths, the second polarity beingopposite the first polarity. Moreover, the capacitive sub-stage may be adistributed capacitive sub-stage.

In some embodiments, the capacitive sub-stage and the inductivesub-stage may inject substantially the same amount of crosstalk as afunction of time so as to be substantially self-cancelling atfrequencies up to 2 GHz. The second crosstalk compensation stage may bea first trace of the first differential pair on a first side of aflexible printed circuit board and a second trace of the seconddifferential pair on a second side of the flexible printed that at leastpartially overlaps the first trace. The first trace may be part of a tipconductive path and the second trace may be part of a ring conductivepath. At least one of the first trace or the second trace may be awidened trace that is configured to have increased capacitive couplingwith the other of the first trace or the second trace. Moreover, thewidths of these traces and/or the degree of overlap of these traces maybe selected such that the amounts of inductive and capacitive crosstalkinjected in the second stage match.

While the example above illustrates a jack that implements the crosstalkcompensation scheme of FIG. 14 between pairs 1 and 3 of an RJ-45 jack,it will be appreciated that this scheme may be used on other paircombinations. For example, the same scheme may be used with respect topairs 1 and 2 and/or with respect to pairs 1 and 4. In such embodiments,the capacitive and inductive second stage compensation would be injectedbetween so-called “like” conductors of the pairs at issue (i.e., betweenthe tip conductive paths of each pair or between the ring conductivepaths of each pair).

Pursuant to still further embodiments of the present invention, theleadframe may be designed so that the current flow in at least some ofthe jackwire contacts flows in a direction that is generally oppositethe direction in which the current flows in other of the jackwirecontacts. FIGS. 16 and 17 are schematic plan views of flexible printedcircuit boards that have leadframe designs in which the signal currentflows in opposite directions.

As shown in FIG. 16, in one embodiment, a flexible printed circuit board630 is provided that is designed so that each tip jackwire contact(i.e., jackwire contacts 140-1, 140-3, 140-5 and 140-7) may be designedso that the signal current carrying path will flow from the plug contactregion through the front portion of the tip jackwire contact 140 andeach ring jackwire contact (i.e., jackwire contacts 140-2, 140-4, 140-6and 140-8) may be designed so that the signal current carrying path willflow from the plug contact region through the rear portion of the ringjackwire contact 140. This may be accomplished by connecting the traces174-1, 174-3, 174-5 and 174-7 to the metal-plated vias 139-1, 139-3,139-5 and 139-7, respectively that receive the front portion of therespective tip jackwire contacts 140. In this embodiment, the flexibleprinted circuit board 630 will typically be implemented as a singleflexible printed circuit board to facilitate routing the traces 174between the front portion of the tip jackwire contacts 140 and theirrespective IDCs 170. Additionally, the first stage capacitive crosstalkcompensation may be implemented using a flexible printed circuit boardthat is mounted on the jackwire contacts (as in the embodiments depictedin FIGS. 10-13) in order to keep the first stage crosstalk compensationat a very small delay. As shown in FIG. 16, the conductive traces 174-1,174-3, 174-5 and 174-7 may be routed along the portions of the flexibleprinted circuit board 630 that define the outer edges of thelongitudinal slots 133.

The flexible printed circuit board 630 may be used in the communicationsinsert 120 that is discussed above with respect to FIGS. 3-9 as areplacement for flexible printed circuit board 130. A communicationsinsert that includes flexible printed circuit board 630 will have signalcurrent carrying paths that flow along the tip jackwire contacts 140toward the front of the flexible printed circuit board 630 and will havesignal current carrying paths that flow along the ring jackwire contacts140 toward the rear of the flexible printed circuit board 630. Bychanging the direction of the current flow through every other jackwirecontact 140, the jackwire contacts 140 may be made to be compensating inthat compensating crosstalk may be introduced between the pairs in theleadframe. It will be appreciated that in other embodiments the flexibleprinted circuit board could be designed so that the signal current wouldflow toward the front of the flexible printed circuit board in each ringjackwire contact 140 and toward the rear of the flexible printed circuitboard in each tip jackwire contact 140.

FIG. 17 illustrates a flexible printed circuit board 630′ according toyet further embodiments of the present invention. As can be seen fromFIG. 17, in this embodiment the signal current carrying path through thejackwire contacts 140-3 and 140-6 of pair 3 flow toward the front of theflexible printed circuit board 630′ while the signal current carryingpath through the remaining six jackwire contacts 140 flow toward therear of the flexible printed circuit board 630′. This design may achievecrosstalk neutrality between pairs 1 and 3, between pairs 2 and 3 andbetween pairs 3 and 4 in the leadframe. Once again, the first stagecapacitive crosstalk compensation may be implemented using a flexibleprinted circuit board that is mounted on the jackwire contacts (as inthe embodiments depicted in FIGS. 10-13) in order to keep the firststage crosstalk compensation at a very small delay.

In the flexible printed circuit board 630′, the traces that run from themetal-plated vias 139 to the IDCs may be routed in pairs to formdifferential transmission lines on the flexible printed circuit board.For example, in the embodiment of FIG. 17, the conductive traces 174-3and 174-6 may be run side-by-side as a pair across the flexible printedcircuit board, as is depicted in the figure. However, in otherembodiments, the conductive traces of some or all of the differentialpairs may be run in overlapping fashion on opposite sides of theflexible printed circuit board 630′. This arrangement may improve thereturn loss of the differential transmission lines on the flexibleprinted circuit board 630′.

Pursuant to still further embodiments of the present invention,communications jacks are provided which may exhibit improved return losson their differential transmission lines. This improved return loss maybe achieved, for example, by inductively and/or capacitivelyself-coupling the two conductive paths of the differential transmissionlines. This self-coupling may help counteract the loads placed on thedifferential transmission lines by the high levels of crosstalkcompensation that may be necessary to counteract the offending crosstalk(particularly for high frequency signals), and hence may provideimproved return loss on the transmission lines.

The above-described design may also be used to compensate for differentplug penetration depths into the communications jack. In particular, asis known to those of skill in the art, when an RJ-45 plug is insertedinto the plug aperture of an RJ-45 jack such that the latch on the pluglocks the plug within the plug aperture, some degree of “play” willstill be provided in terms of how far that the plug penetrates into theplug aperture. Thus, in practice, one may not know the exact penetrationof the plugs that will be used in a given jack; instead, one willtypically only know that the plug penetration depth may fall within arange specified in relevant industry standard documents. Thisuncertainty regarding plug penetration depth may make it more difficultto effectively cancel the offending crosstalk injected in the plug.

Pursuant to embodiments of the present invention, the compensatingcrosstalk that is injected in a communications jacks may be designed sothat changes in the amount of compensating crosstalk that is injectedbetween the differential pairs (e.g., between pairs 1 and 3) that resultfrom different plug penetration depths are offset by substantially equalmagnitude and opposite polarity changes in the amount of compensatingcrosstalk injected by the jack. In such communications jacks, thecrosstalk compensation scheme may be relatively insensitive to plugpenetration depth, and may therefore consistently provide bettercrosstalk compensation. One way of achieving this is to have the currentrun in different directions along the jackwire contacts of differentdifferential pairs (e.g., differential pairs 1 and 3), as discussedabove.

FIG. 18 illustrates a flexible printed circuit board 730 for acommunications jack according to yet additional embodiments of thepresent invention that may provide this improved return lossperformance. The flexible printed circuit board 730 may be used in placeof the flexible printed circuit board 130 in the communications insert120 discussed above with respect to FIGS. 3-9. As the flexible printedcircuit board 730 is quite similar to the flexible printed circuit board130, the discussion below will focus on the additional feature (namely areturn loss improvement circuit) that is included on the flexibleprinted circuit board 730.

As shown in FIG. 18, a return loss improvement circuit 780 is providedon the flexible printed circuit board 730. The return loss improvementcircuit 780 is implemented as a pair of spirals 781, 782 that areincluded in the conductive path 174-3 that connects jackwire contact140-3 to its respective IDC 170-3. The spiral 781 is on the top side offlexible printed circuit board 730. A segment of the conductive path174-3 connects the metal-plated aperture 139-11 to the outer end ofspiral 781. The spiral 781 winds inwardly (clockwise in FIG. 18) inincreasingly smaller generally circular sections that are immediatelyadjacent each other and which have substantially the same instantaneouscurrent direction. The immediate adjacency of trace sections havingsubstantially the same instantaneous current direction in spiral 781causes self-coupling between the adjacent windings of the spiral 781,which in turn triggers an increase in localized inductance.

As is discussed, for example, in U.S. Pat. No. 7,326,089, issued Feb. 5,2008, the entire content of which is incorporated herein by reference asif set forth in its entirety, the use of self-coupling conductors thatgenerate a localized increase in self-inductance may be used to improvethe return loss on one more differential transmission lines through acommunications connector. In particular, by judicious selection of theportions of a conductive path that are immediately adjacent each otherwith identical or substantially identical instantaneous currentdirection it may be possible to control the input impedance of adifferential transmission line through a mated plug jack combination,and, consequently, it may be possible to control the return loss of thedifferential transmission line. As a result, the jack of the mated plugjack combination can withstand the increased crosstalk compensation thatmay be necessary to achieve, in a mated plug jack combination, elevatedfrequency signal transmission while still experiencing acceptable levelsof return loss.

As is further shown in FIG. 18, when a signal reaches the inner end ofthe spiral 781 it is coupled onto the conductive via 783 that extendsbetween the top and bottom layers of the flexible printed circuit board730. The signal then traverses the spiral 782, which winds outwardly(clockwise in FIG. 18) in increasingly larger generally circularsections that are immediately adjacent each other and which havesubstantially the same instantaneous current direction. The immediateadjacency of trace sections having substantially the same instantaneouscurrent direction in spiral 782 causes self-coupling between theadjacent rings of the spiral 782, which in turn triggers an increase inlocalized inductance. The outer end of spiral 782 connects to the via172-3.

The spiral 782 substantially overlaps the spiral 781. Additionally, theinstantaneous current direction of a signal traversing the spirals 781and 782 will be the same (i.e., depending on the current polarity,either a signal will flow through both spirals 781, 782 in the clockwisedirection or will flow through both spirals 781, 782 in thecounter-clockwise direction). Consequently, localized increases ininductance along trace 174-3 will be obtained by (1) the couplingbetween immediately adjacent sections in the spiral 781, (2) thecoupling between immediately adjacent sections in the spiral 782 and (3)the coupling between the overlapping sections of spirals 781 and 782.Accordingly, significant amounts of inductive self-coupling may beachieved. This is particularly true when the spirals 781, 782 areimplemented on a flexible printed circuit board because, as discussedabove, flexible printed circuit boards may have very thin dielectriclayers and hence substantial amounts of inductive coupling may beachieved between overlapping traces on a flexible printed circuit board.In other embodiments, the spirals may be arranged to reduce theself-inductance of the path, by having the current running in oppositedirections in the two spiral paths. Thus, it will be appreciated thatthe current direction in the two spirals may be selected based onwhether or not more or less self-inductance is desirable. It will alsobe appreciated that geometric arrangements other than spirals may beused to achieve segments on the two conductors of a differentialtransmission line that have substantially the same or substantiallyopposite instantaneous current directions.

In addition, the arrangement of the spirals 781, 782 that are depictedin FIG. 18 may also generate substantial amounts of self-capacitance onconductive path 174-3. In particular, given the thin nature of thedielectric layer of the flexible printed circuit board 730, the spiral781 will capacitively couple with the spiral 782. This capacitivecoupling may further improve the return loss on the differentialtransmission line that includes conductive trace 174-3. Moreover,heightened levels of capacitive self-coupling may be achieved bywidening the conductive traces that are used to form the spirals 781,782.

By generating both self-inductance and self-capacitance along theconductive trace 174-3 it may be possible to provide a significantimprovement in the return loss of the differential transmission linethat includes conductive trace 174-3. It may be difficult, in someinstances, to provide this degree of improvement in return loss bygenerating only self-inductance as the amount of room or “real estate”on the printed circuit boards used in many communications connectorssuch as RJ-45 jacks may be quite limited, and this constraint may limitthe length of the inductively self-coupling sections. In someembodiments, the amount of capacitive coupling generated along aconductive path such as conductive path 174-3 may be at least half theamount of the inductive coupling. In some embodiments, the amount ofcapacitive coupling generated along the conductive path may exceed theamount of inductive coupling.

Moreover, pursuant to some embodiments of the present invention, theratio of the self-capacitance to the self-inductance may be tuned toimprove the return loss on the transmission line. In particular, it hasbeen discovered that by generating both self-inductance andself-capacitance along a differential transmission line that resonancesmay be created. By adjusting the relative amount of self-capacitance toself-inductance these resonances may be tuned so as to create a localmaxima in the return loss spectra.

While the spirals 781, 782 are used to provide trace segments alongconductive path 174-3 that have substantially the same instantaneouscurrent direction, it will be appreciated that other traceconfigurations may be used. For example, two parallel trace sections790, 792 that have the same instantaneous current direction may be usedinstead, as is shown schematically in FIG. 18A. It will also beappreciated that the improvement in return loss may be achieved even ifthe traces do not have the exact same instantaneous current direction.Thus, it will be appreciated that the trace segments need not be exactlyparallel as shown in FIG. 18B.

While only one pair of spirals 781, 782 is illustrated in FIG. 18, itwill be appreciated that in other embodiments more than one pair ofspirals may be provided and/or that the spirals may be included ondifferent of the conductive paths 174. By way of example, in anotherembodiment, a second pair of spirals may be provided on conductive trace174-6 that may be identical to the pair of spirals 781, 782. In stillother embodiments, pairs of spirals may be included, for example, onconductive trace 174-4 and/or on conductive trace 174-5. While theinclusion of self-coupling sections in the conductors of pairs 1 and 3may often be sufficient for improving the return loss performance ofthose pairs; it will also be appreciated that this concept can beapplied to either or both of pairs 2 and 4, or to other conductors ofjacks that employ different numbers of conductors (e.g., a sixteenconductor jack). Also, although in the illustrated embodiment theself-coupling is achieved both by the adjacency of self-couplingsections on the same layer of the flexible printed circuit board and bythe overlapping nature of the two spirals that are provided on differentlayers of the flexible printed circuit board, it will be appreciatedthat in other embodiments the self-coupling may only occur in one ofthese two dimensions. Moreover, the skilled artisan will recognize thatmany different conductive paths that implement these concepts may beemployed. Thus, it will be appreciated that FIG. 18 merely shows anexample of this concept, and is not intended to be limiting.

FIG. 19 is a schematic plan view of both the top and bottom layers of aflexible printed circuit board 730′ according to further embodiments ofthe present invention. The flexible printed circuit board 730′ is quitesimilar to the flexible printed circuit board 730 discussed above. Thus,the description that follows will focus on the differences between thetwo flexible printed circuit boards 730, 730′.

As is readily apparent, the difference between the two flexible printedcircuit board designs 730, 730′ is that the flexible printed circuitboard 730′ replaces the return loss improvement circuit 780 (whichcomprised spirals 781 and 782) with a return loss improvement circuit780′. The return loss improvement circuit 780′ operates in a similarmanner to circuit 780, but generates the localized increases ininductance and capacitance using the two conductive paths of adifferential transmission line as opposed to by using only one of theconductive paths. In the embodiment of FIG. 19, the return lossimprovement circuit is implemented on pair 1 as opposed to pair 3 as thetraces of pair 1 are more conveniently located near each other.

In particular, as shown in FIG. 19, the return loss improvement circuit780′ is formed by running a section 781′ of conductive path 174-4 on thebottom side of the flexible printed circuit board 730′ and by running asection 782′ of conductive path 174-5 on the top side of the flexibleprinted circuit board 730′ above section 781′. As the currents on thetwo conductive paths 174-4, 174-5 are 180 degrees out of phase (sincethe two conductive paths 174-4 and 174-5 form a differentialtransmission line), one of the traces 174-4 or 174-5 (here trace 174-4)is routed in the opposite direction by, for example, including a pair of180 degree turns in the trace 174-4 and routing the section 781′ oftrace 174-4 that is between the two 180 degree turns underneath section782′ of conductive trace 174-3. As explained, for example, in U.S. Pat.No. 7,264,516, issued Sep. 4, 2007, the entire contents of which areincorporated herein by reference, the trace sections 781′, 782′ that areimmediately adjacent each other and that follow substantially parallelpaths will have the same instantaneous current direction. The immediateadjacency of this arrangement causes coupling between the sections 781′,782′ which in turn triggers an increase in localized inductance.

Moreover, since the sections 781′, 782′ are implemented on oppositesides of a flexible printed circuit board 730′, the sections 781′, 782′will both inductively couple and capacitively couple. The techniques foradjusting the relative amounts of capacitive and inductive coupling thatare discussed above with respect to FIG. 18 may also be applied in theembodiment of FIG. 19 to generate a local maximum in the return lossspectrum and to locate that local maximum in a location that providesdesired return loss performance for the differential transmission line.For example, FIG. 19A schematically illustrates how the above-describedself-coupling may generate a local maximum in the return loss spectrum(i.e., the return loss plotted as a function of frequency) for adifferential transmission line. In particular, FIG. 19A depicts thereturn loss of an example differential transmission line as a functionof frequency (plot 704). A possible return loss limit currently underconsideration by the TIA standards body is also depicted in FIG. 19A(plot 702). As shown in FIG. 19A, at higher frequencies it may bedifficult to meet such a return loss limit. By providing sections on atleast one of the conductive paths of the differential transmission linethat both inductively self-couple and capacitively self-couple, it maybe possible to provide improved return loss, as shown by plot 706 inFIG. 19A. This improvement may take the form of a local maximum 708 inthe return loss spectrum. By adjusting the relative amounts ofself-inductance and self-capacitance injected on the conductive path ofthe differential transmission line, the location of this local maximummay be adjusted. In some embodiments, the local maximum may be locatednear a maximum operating frequency for the connector at issue (e.g.,between 60% and 125% of the maximum operating frequency). This mayprovide for a significant improvement in the return loss of thedifferential transmission line at issue in the region where improvedperformance may be most needed. The ratio of self-inductance toself-capacitance can be adjusted, for example, by adjusting the widthsof the self-coupling traces (as increased width generates relativelymore self-capacitance) and/or by adjusting the amount of overlap of thetraces on the opposite sides of the printed circuit board.

Pursuant to still further embodiments of the present invention,crosstalk compensation circuits are provided that are implemented onflexible printed circuit boards in order to achieve high amounts ofcrosstalk compensation with very short coupling sections. As discussedabove, the dielectric layers on flexible printed circuit boards may bevery thin (e.g., 1 mil). This allows for significant amounts of couplingbetween overlapping traces that are implemented on either side if theflexible printed circuit board. As inductive crosstalk compensationrequires current flow, it necessarily is spread out in time. Whencrosstalk compensation is spread over time, it necessarily involves anassociated delay. As all other parameters being equal, improvedcrosstalk compensation may generally be provided the shorter the delay,the ability to introduce large amounts of inductive crosstalkcompensation within very short trace segments may be desirable.Communications jacks that implement this technique are provided pursuantto further embodiments of the present invention.

In particular, FIG. 20 is a schematic plan view of both the top andbottom layers of a flexible printed circuit board 830 of acommunications insert according to even further embodiments of thepresent invention. As shown in FIG. 20, the flexible printed circuitboard 830 is very similar to the flexible printed circuit board 130discussed above. Thus, the description that follows will focus on thedifferences between the two flexible printed circuit boards 130, 830. Itwill be appreciated that the flexible printed circuit board 830 may beused in place of the flexible printed circuit board 130 in thecommunications insert 120 of jack 100.

As shown in FIG. 20, the inductive crosstalk compensation circuits 178-3and 178-4 of flexible printed circuit board 130 are replaced withinductive crosstalk compensation circuits 178-3′ and 178-4′. Onedifference between circuits 178-3, 178-4 and 178-3′, 178-4′ are that theformer circuits provide inductive crosstalk compensation by inductivelycoupling traces that run side-by-side on the same layer of the flexibleprinted circuit board 130 while the latter circuits provide inductivecrosstalk compensation by inductively coupling traces that run inoverlapping fashion on opposite sides of the flexible printed circuitboard 830. As noted above, much higher levels of inductive coupling canbe achieved via this arrangement, and hence the length of the inductivecoupling sections may be shortened. The effect of this is to push thecentroid of the inductive coupling sections closer to the plug contactregions of the jackwire contacts 140, and hence at a smaller delay fromthe plug contact region. This may improve the crosstalk cancellation,particularly for high frequency signals.

Pursuant to still further embodiments of the present invention,crosstalk compensation circuits are provided in which crosstalkcompensation is optimized by minimizing the longitudinal signal travelbetween offending crosstalk and the location where like polarizedconductive traces from two different pairs are made to couple. This isachieved by transversely routing these conductive traces throughouttheir travel from where they are intercepted by their correspondingjackwire contacts to where they couple by running parallel in anoverlapped or side-by-side manner. In particular, FIG. 21 is a schematicplan view of both the top and bottom layers of a flexible printedcircuit board 830′ of a communications insert according to such anembodiment. As shown in FIG. 21, the flexible printed circuit board 830′is very similar to the flexible printed circuit board 830 discussedabove. Thus, the description that follows will focus on the differencesbetween the two flexible printed circuit boards 830 and 830′. It will beappreciated that the flexible printed circuit board 830′ may be used inplace of the flexible printed circuit board 130 in the communicationsinsert 120 of jack 100. The only difference between circuits 830 and830′ is that the former circuit provides each of the inductive crosstalkcouplings 178-3′ and 178-4′ after a longitudinal signal travel, indictedby dl in FIG. 20, while by contrast the inductive crosstalk couplings178-3″ and 178-4″ are each provided in the latter circuit without thesignal having to incur such a longitudinal travel. The effect of this isto reduce the delay between the offending crosstalk and the locationwhere the inductive crosstalk is commenced which would improve thecrosstalk cancellation, particularly for high frequency signals.

For very high frequency signals, reducing or minimizing the amount ofthe delay before the inductive (and possibly capacitive) crosstalkcompensation is injected by the inductive crosstalk coupling circuits178-3″ and 178-4″ may be important. Thus, in some embodiments, the startof the coupling sections 178-3″ and 178-4″ may be located along atransverse plane defined by the conductive vias 139-12 and 139-14 thathold the back ends of jackwire contacts 140-4 and 140-6. In suchembodiments, a first distance that is defined as the distance betweenthe top of via 139-12 (i.e., the intercept of jackwire contact 140-4 andthe top surface of the flexible printed circuit board 830′) and the topof via 139-14 (i.e., the intercept of jackwire contact 140-6 and the topsurface of the flexible printed circuit board 830′) may be substantiallyequal to a second distance that is defined as the sum of (1) thedistance between the top of via 139-12 and the coupling section 178-3″and (2) the distance between the top of via 139-14 and the couplingsection 178-3″. In other embodiments, the second distance may be as muchas twice the first distance, although the greater the second distancethe more that the impact of delay may negatively impact crosstalkcancellation for high frequency signals.

While embodiments of the present invention have primarily been discussedherein with respect to communications jacks that include eightconductive paths that are arranged as four differential pairs ofconductive paths, it will be appreciated that the concepts describedherein are equally applicable to jacks that include other numbers ofdifferential pairs.

While the present invention has been described above primarily withreference to the accompanying drawings, it will be appreciated that theinvention is not limited to the illustrated embodiments; rather, theseembodiments are intended to fully and completely disclose the inventionto those skilled in this art. In the drawings, like numbers refer tolike elements throughout. Thicknesses and dimensions of some componentsmay be exaggerated for clarity.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper”, “top”, “bottom” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation in addition tothe orientation depicted in the figures. For example, if the device inthe figures is turned over, elements described as “under” or “beneath”other elements or features would then be oriented “over” the otherelements or features. Thus, the exemplary term “under” can encompassboth an orientation of over and under. The device may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein interpreted accordingly. As onespecific example, various features of the communications jacks of thepresent invention are described as being, for example, on or above a topsurface of a printed circuit board. It will be appreciated that ifelements are on the bottom surface of a printed circuit board, they willbe located on the top surface if the jack is rotated 180 degrees. Thus,the term “top surface” can refer to either the top surface or the bottomsurface as the difference is a mere matter of orientation.

Well-known functions or constructions may not be described in detail forbrevity and/or clarity. As used herein the expression “and/or” includesany and all combinations of one or more of the associated listed items.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”,“comprising”, “includes” and/or “including” when used in thisspecification, specify the presence of stated features, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Herein, the terms “attached”, “connected”, “interconnected”,“contacting”, “mounted” and the like can mean either direct or indirectattachment or contact between elements, unless stated otherwise.

Although exemplary embodiments of this invention have been described,those skilled in the art will readily appreciate that many modificationsare possible in the exemplary embodiments without materially departingfrom the novel teachings and advantages of this invention. Accordingly,all such modifications are intended to be included within the scope ofthis invention as defined in the claims. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

That which is claimed is:
 1. An RJ-45 communications jack having alongitudinal axis, comprising: a housing having a plug aperture that isconfigured to receive a mating RJ-45 plug along the longitudinal axis; aflexible printed circuit board having a first conductive path and asecond conductive path that form a first differential pair of conductivepaths and a third conductive path and a fourth conductive path that forma second differential pair of conductive paths; a first jackwire contactthat is electrically connected to the first conductive path; a secondjackwire contact that is electrically connected to the second conductivepath; a third jackwire contact that is electrically connected to thethird conductive path; a fourth jackwire contact that is electricallyconnected to the fourth conductive path; wherein a section of the firstconductive path is on a first side of the flexible printed circuit boardand a section of the third conductive path is on a second side of theflexible printed circuit board that is opposite the first side, andwherein the section of the first conductive path and the section of thethird conductive path are configured to form a coupling section in whichthe first and third conductive paths both inductively and capacitivelycouple.
 2. The communications jack of claim 1, wherein the section ofthe first conductive path and the section of the third conductive paththat form the coupling section partially overlap but do not completelyoverlap.
 3. The communications jack of claim 2, wherein an amount ofcapacitive coupling between the section of the first conductive path andthe section of the third conductive path is at least half an amount ofinductive coupling between the section of the first conductive path andthe section of the third conductive path.
 4. The communications jack ofclaim 1, wherein the coupling section is configured so that thecapacitive coupling has a first polarity and the inductive coupling hasa second polarity that is opposite the first polarity.
 5. Thecommunications jack of claim 1, wherein a first amount of capacitivecoupling that the coupling section is configured to generate issubstantially equal to a second amount of capacitive coupling that thecoupling section is configured to generate.
 6. The communications jackof claim 1, wherein the first conductive path is a tip conductive pathand the third conductive path is a ring conductive path.
 7. Thecommunications jack of claim 1, wherein the coupling section isconfigured so that the magnitude of the capacitive coupling per unitlength is substantially equal to the magnitude of the inductive couplingper unit length.
 8. The communications jack of claim 1, wherein at leasta portion of the first conductive path that is in the coupling sectionis widened as compared to the remainder of the first conductive path. 9.A communications jack, comprising: a flexible printed circuit board; afirst conductive path electrically connecting a first input of the jackand a first output of the jack; a second conductive path electricallyconnecting a second input of the jack and a second output of the jack,wherein the first and second conductive paths comprise a firstdifferential pair of conductive paths for transmitting a firstinformation signal; a third conductive path electrically connecting athird input of the jack and a third output of the jack; a fourthconductive path electrically connecting a fourth input of the jack and afourth output of the jack, wherein the third and fourth conductive pathscomprise a second differential pair of conductive paths for transmittinga second information signal; and a return loss improvement circuit thatcomprises a first section of the first conductive path and a secondsection of the second conductive path that have substantially the sameinstantaneous current directions, wherein the first section and thesecond section are positioned to both capacitively and inductivelycouple with each other, wherein the first section of the firstconductive path is on a first side of the flexible printed circuit boardand the second section of the second conductive path is on a second sideof the flexible printed circuit board that is opposite the first side.10. The communications jack of claim 9, wherein the ratio of thecapacitive coupling to the inductive coupling in the return lossimprovement circuit is selected to provide a local maximum in a returnloss spectrum.